Upload COCOM

README.md

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+---
+library_name: transformers
+tags: []
+---
+
+# Model Card for Model ID
+
+<!-- Provide a quick summary of what the model is/does. -->
+
+
+
+## Model Details
+
+### Model Description
+
+<!-- Provide a longer summary of what this model is. -->
+
+This is the model card of a 🤗 transformers model that has been pushed on the Hub. This model card has been automatically generated.
+
+- **Developed by:** [More Information Needed]
+- **Funded by [optional]:** [More Information Needed]
+- **Shared by [optional]:** [More Information Needed]
+- **Model type:** [More Information Needed]
+- **Language(s) (NLP):** [More Information Needed]
+- **License:** [More Information Needed]
+- **Finetuned from model [optional]:** [More Information Needed]
+
+### Model Sources [optional]
+
+<!-- Provide the basic links for the model. -->
+
+- **Repository:** [More Information Needed]
+- **Paper [optional]:** [More Information Needed]
+- **Demo [optional]:** [More Information Needed]
+
+## Uses
+
+<!-- Address questions around how the model is intended to be used, including the foreseeable users of the model and those affected by the model. -->
+
+### Direct Use
+
+<!-- This section is for the model use without fine-tuning or plugging into a larger ecosystem/app. -->
+
+[More Information Needed]
+
+### Downstream Use [optional]
+
+<!-- This section is for the model use when fine-tuned for a task, or when plugged into a larger ecosystem/app -->
+
+[More Information Needed]
+
+### Out-of-Scope Use
+
+<!-- This section addresses misuse, malicious use, and uses that the model will not work well for. -->
+
+[More Information Needed]
+
+## Bias, Risks, and Limitations
+
+<!-- This section is meant to convey both technical and sociotechnical limitations. -->
+
+[More Information Needed]
+
+### Recommendations
+
+<!-- This section is meant to convey recommendations with respect to the bias, risk, and technical limitations. -->
+
+Users (both direct and downstream) should be made aware of the risks, biases and limitations of the model. More information needed for further recommendations.
+
+## How to Get Started with the Model
+
+Use the code below to get started with the model.
+
+[More Information Needed]
+
+## Training Details
+
+### Training Data
+
+<!-- This should link to a Dataset Card, perhaps with a short stub of information on what the training data is all about as well as documentation related to data pre-processing or additional filtering. -->
+
+[More Information Needed]
+
+### Training Procedure
+
+<!-- This relates heavily to the Technical Specifications. Content here should link to that section when it is relevant to the training procedure. -->
+
+#### Preprocessing [optional]
+
+[More Information Needed]
+
+
+#### Training Hyperparameters
+
+- **Training regime:** [More Information Needed] <!--fp32, fp16 mixed precision, bf16 mixed precision, bf16 non-mixed precision, fp16 non-mixed precision, fp8 mixed precision -->
+
+#### Speeds, Sizes, Times [optional]
+
+<!-- This section provides information about throughput, start/end time, checkpoint size if relevant, etc. -->
+
+[More Information Needed]
+
+## Evaluation
+
+<!-- This section describes the evaluation protocols and provides the results. -->
+
+### Testing Data, Factors & Metrics
+
+#### Testing Data
+
+<!-- This should link to a Dataset Card if possible. -->
+
+[More Information Needed]
+
+#### Factors
+
+<!-- These are the things the evaluation is disaggregating by, e.g., subpopulations or domains. -->
+
+[More Information Needed]
+
+#### Metrics
+
+<!-- These are the evaluation metrics being used, ideally with a description of why. -->
+
+[More Information Needed]
+
+### Results
+
+[More Information Needed]
+
+#### Summary
+
+
+
+## Model Examination [optional]
+
+<!-- Relevant interpretability work for the model goes here -->
+
+[More Information Needed]
+
+## Environmental Impact
+
+<!-- Total emissions (in grams of CO2eq) and additional considerations, such as electricity usage, go here. Edit the suggested text below accordingly -->
+
+Carbon emissions can be estimated using the [Machine Learning Impact calculator](https://mlco2.github.io/impact#compute) presented in [Lacoste et al. (2019)](https://arxiv.org/abs/1910.09700).
+
+- **Hardware Type:** [More Information Needed]
+- **Hours used:** [More Information Needed]
+- **Cloud Provider:** [More Information Needed]
+- **Compute Region:** [More Information Needed]
+- **Carbon Emitted:** [More Information Needed]
+
+## Technical Specifications [optional]
+
+### Model Architecture and Objective
+
+[More Information Needed]
+
+### Compute Infrastructure
+
+[More Information Needed]
+
+#### Hardware
+
+[More Information Needed]
+
+#### Software
+
+[More Information Needed]
+
+## Citation [optional]
+
+<!-- If there is a paper or blog post introducing the model, the APA and Bibtex information for that should go in this section. -->
+
+**BibTeX:**
+
+[More Information Needed]
+
+**APA:**
+
+[More Information Needed]
+
+## Glossary [optional]
+
+<!-- If relevant, include terms and calculations in this section that can help readers understand the model or model card. -->
+
+[More Information Needed]
+
+## More Information [optional]
+
+[More Information Needed]
+
+## Model Card Authors [optional]
+
+[More Information Needed]
+
+## Model Card Contact
+
+[More Information Needed]

adapters.pth

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+oid sha256:1c3a419bb9f29ee5817df83071ee39d3c0d32f67731cefe6e752c42d4fd14567
+size 80867374

compressor/compressor.pth

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+size 2471719312

compressor/mlp.pth

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+size 91218544

config.json

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+{
+  "_attn_implementation_autoset": true,
+  "attn_implementation": null,
+  "auto_map": {
+    "AutoConfig": "modelling_pisco.COCOMConfig",
+    "AutoModel": "modelling_pisco.COCOM"
+  },
+  "compr_base_model_name": null,
+  "compr_bidirectional": false,
+  "compr_every_n_layer": null,
+  "compr_mlp_hidden_dim": 8096,
+  "compr_model_name": "meta-llama/Llama-3.2-1B-Instruct",
+  "compr_n_layers": null,
+  "compr_rate": 16,
+  "compr_rms_norm": false,
+  "compr_use_mlp": true,
+  "decoder_model_name": "Qwen/Qwen2-7B-Instruct",
+  "device_map": "auto",
+  "different_mem_tokens": true,
+  "doc_max_length": 128,
+  "generation_top_k": 1,
+  "kbtc_training": false,
+  "load_adapters": true,
+  "lora": true,
+  "lora_compressor": false,
+  "lora_r": 16,
+  "lora_r_compressor": 16,
+  "model_type": "COCOM",
+  "optimize_mem_tokens": true,
+  "quantization": "no",
+  "sep": true,
+  "training_form": "both_separately",
+  "transformers_version": "4.48.0"
+}

decoder_first_last_layers.pth

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+oid sha256:819493121aa58c390992e975881ddfe776f77b282ab48f2296c06493cf3d9217
+size 2174156420

modelling_pisco.py

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+import warnings
+import os
+import torch
+import gc
+
+from torch import nn
+from jinja2.exceptions import TemplateError
+from peft import LoraConfig
+from transformers import AutoModelForCausalLM, AutoTokenizer, BitsAndBytesConfig, PreTrainedModel, PretrainedConfig, AutoModel, AutoConfig
+from huggingface_hub import hf_hub_download, HfApi, hf_hub_url
+
+
+def get_local_file_path(pretrained_model_name_or_path, filename) -> str:
+    """
+    loads from the hub if necessary, and returns path of downloaded file
+    if local checkpoint, also returns path to local file :)
+    """
+    try:
+        # If loading from Hugging Face Hub
+        local_path = hf_hub_download(repo_id=pretrained_model_name_or_path, filename=filename)
+    except Exception as e:
+        # If loading from a local directory
+        local_path = os.path.join(pretrained_model_name_or_path, filename)
+        
+    return local_path
+
+
+def get_first_layers_model(base_model_name: str, n_layers: int, attn_implementation: str = 'flash_attention_2'):
+    """
+    Builds a model comprising only the n_layers first layer of the base_model_name
+    (it keeps the embedding and head layers)
+    """
+    full_model = AutoModelForCausalLM.from_pretrained(base_model_name)
+    
+    # Create a new config for a model with fewer layers (e.g., 3 layers)
+    custom_config = AutoConfig.from_pretrained(base_model_name)
+    custom_config.num_hidden_layers = n_layers 
+    first_layers_model = AutoModelForCausalLM.from_config(config=custom_config, attn_implementation=attn_implementation, torch_dtype=torch.bfloat16)       
+    
+    # Load the state dict of the full model
+    full_state_dict = full_model.state_dict()
+    custom_state_dict = first_layers_model.state_dict()
+    kept_state_dict = {k:v for k,v in full_state_dict.items() if k in custom_state_dict}
+    
+    first_layers_model.load_state_dict(kept_state_dict, strict=True)
+    
+    del full_model
+    torch.cuda.empty_cache()
+    gc.collect()
+    
+    return first_layers_model
+
+
+def get_every_n_layer_model(base_model_name: str, every_n_layer: int, attn_implementation: str = 'flash_attention_2'):
+    """
+    Builds a model comprising 1 every every_n_layer layer of the base_model_name
+    (it keeps the embedding and head layers)
+    """
+    full_model = AutoModelForCausalLM.from_pretrained(base_model_name)
+    n_kept_layers = full_model.config.num_hidden_layers // every_n_layer
+    
+    print(f'New model with 1/{every_n_layer} from {base_model_name} will have {n_kept_layers} layers')
+    
+    custom_config = AutoConfig.from_pretrained(base_model_name)
+    custom_config.num_hidden_layers = n_kept_layers 
+    custom_model = AutoModelForCausalLM.from_config(config=custom_config, 
+                                                    attn_implementation=attn_implementation, 
+                                                    torch_dtype=torch.bfloat16)       
+    full_state_dict = full_model.state_dict()
+    custom_state_dict = custom_model.state_dict()
+    
+    # Filter out every Nth layer and rename to form a new state dict
+    kept_state_dict = {}
+    for key, value in full_state_dict.items():
+        if ".layers." in key:
+            # Extract layer index
+            layer_idx = int(key.split(".layers.")[1].split(".")[0])
+            # Check if it's an Nth layer
+            if layer_idx % every_n_layer == 0:
+                # Adjust layer index for the smaller model
+                new_layer_idx = layer_idx // every_n_layer
+                # print('replacing', f".layers.{layer_idx}.", f".layers.{new_layer_idx}.")
+                new_key = key.replace(f".layers.{layer_idx}.", f".layers.{new_layer_idx}.")
+                if new_key in custom_state_dict:
+                    kept_state_dict[new_key] = value
+        else:
+            # Keep non-layer-specific parameters
+            if key in custom_state_dict:
+                kept_state_dict[key] = value
+
+    # Load the filtered state dict into the custom model
+    custom_model.load_state_dict(kept_state_dict, strict=True)
+    
+    del full_model
+    torch.cuda.empty_cache()
+    gc.collect()
+    
+    return custom_model
+                
+    
+class MistralTrimmed(torch.nn.Module):
+    """
+    Trimmed version of base models for faster compression
+    NB: the name 'MistralTrimmed' suggests it just works with mistral but NO in fact most LLMs are supported !
+    """
+    def __init__(self, 
+                 n_layers: int = 15,
+                 every_n_layer: int = None,
+                 rms_norm: bool = False,
+                 base_model_name: str = 'mistralai/Mistral-7B-Instruct-v0.2',
+                 attn_implementation: str = 'flash_attention_2'):
+        """
+        you can either specify
+        - n_layers to some number: we take the n_layers first layers of the base model.
+        - every_n_layer to some number: in that case we take 1/N layer of the base model
+        The base_model_name is the name of the model from which this model is built.
+        """
+        assert (n_layers is None) ^ (every_n_layer is None), 'Cannot specify both n_layers and every_n_layer for MistralTrimmed'        
+        super().__init__()
+        
+        self.n_layers = n_layers
+        self.every_n_layer = every_n_layer
+        self.base_model_name = base_model_name
+        
+        if n_layers is not None:
+            self.custom_model = get_first_layers_model(self.base_model_name, 
+                                                       n_layers, 
+                                                       attn_implementation=attn_implementation)
+        
+        else:
+            self.custom_model = get_every_n_layer_model(self.base_model_name, 
+                                                        every_n_layer, 
+                                                        attn_implementation=attn_implementation)
+            
+        self.custom_model = self.custom_model.bfloat16()
+        self.custom_model.cuda()
+
+        if rms_norm:
+            print('Compressor keeps its original rms norm')
+        else:
+            print('De-activating RMS norm in compressor')
+            # We deactivate the norm: we don't need it here since we want to manipulate stuff within embed space
+            # see https://github.com/huggingface/transformers/blob/v4.45.0/src/transformers/models/mistral/modeling_mistral.py#L699
+            self.custom_model.model.norm = nn.Identity()
+        
+        # Piping useful methods:
+        self.add_adapter = self.custom_model.add_adapter
+        self.set_adapter = self.custom_model.set_adapter
+        self.load_adapter = self.custom_model.load_adapter
+        self.num_parameters = self.custom_model.num_parameters
+        self.resize_token_embeddings = self.custom_model.resize_token_embeddings
+        self.get_input_embeddings = self.custom_model.get_input_embeddings
+        self.get_adapter_state_dict = self.custom_model.get_adapter_state_dict
+        
+        # self.custom_model.gradient_checkpointing_enable()
+        
+        # del self.custom_model.lm_head # THIS FAILS since some models have tie_embeddings=True !
+        # gc.collect()
+        # torch.cuda.empty_cache()    
+
+    def forward(self, input_ids, attention_mask=None):
+        return self.custom_model.model(input_ids, attention_mask, output_hidden_states=True) # we call the .model attribute of the causal LM to avoid the cost of the LM head ! nice huh ?
+    
+    def __call__(self, input_ids, attention_mask=None, output_hidden_states=True):
+        return self.forward(input_ids, attention_mask)
+
+
+class AbstractCompressor(nn.Module):
+    def __init__(self, compr_model_name: str, compr_rate: int, decoder_hidden_size: int):
+        super().__init__()
+        self.compr_model_name = compr_model_name
+        self.compr_rate = compr_rate
+        self.decoder_hidden_size = decoder_hidden_size
+        
+    def forward(self, input_ids, attention_mask, generation_top_k):
+        """
+        input_ids of shape (batch_size, top_k, seq_length)
+        attention_mask of shape (batch_size, top_k, seq_length)
+        generation_top_k: the number of docs
+        """
+        raise NotImplementedError
+    
+    def save_pretrained(self, save_directory):
+        raise NotImplementedError
+
+    def load_pretrained(self, load_directory):
+        raise NotImplementedError
+
+
+class BertCompressor(AbstractCompressor):
+    def __init__(self, 
+                 compr_model_name: str,
+                 compr_rate: int, 
+                 decoder_hidden_size: int, 
+                 mlp_hidden_dim: int = 8192, 
+                 use_mlp: bool = True,
+                 doc_max_length : int = 128,
+                 **kwargs):
+        # TODO use the device_map
+        super().__init__(compr_model_name=compr_model_name, compr_rate=compr_rate, decoder_hidden_size=decoder_hidden_size)
+        if compr_model_name == 'mistral_trimmed':
+            assert 'compr_n_layers' in kwargs
+            self.model = MistralTrimmed(n_layers=kwargs['compr_n_layers'], 
+                                        every_n_layer=kwargs['compr_every_n_layer'], 
+                                        rms_norm=kwargs['compr_rms_norm'],
+                                        base_model_name=kwargs['compr_base_model_name'],
+                                        attn_implementation=kwargs['attn_implementation'])
+            self.tokenizer = AutoTokenizer.from_pretrained(self.model.base_model_name)
+            self.hidden_size = self.model.custom_model.config.hidden_size
+        else:
+            self.model = AutoModel.from_pretrained(compr_model_name, torch_dtype=torch.bfloat16, device_map='auto')
+            self.tokenizer = AutoTokenizer.from_pretrained(compr_model_name, use_fast=True)
+            self.tokenizer.padding_side = "left"
+            self.hidden_size = self.model.config.hidden_size
+            
+        print('Base compressor nb parameters', self.model.num_parameters())
+
+        self.mlp_hidden_dim = mlp_hidden_dim
+        self.use_mlp = use_mlp
+        self.doc_max_length = doc_max_length
+        
+        if self.use_mlp:
+            self.mlp = nn.Sequential(
+                nn.Linear(self.hidden_size, self.mlp_hidden_dim), 
+                nn.ReLU(),
+                nn.Linear(self.mlp_hidden_dim, decoder_hidden_size)
+            ).bfloat16() 
+            self.mlp.cuda()
+        
+        self.n_emb = self.doc_max_length // self.compr_rate
+        
+        mem_tokens = ['<MEM' + str(i) + '>' for i in range(self.n_emb)]
+        self.tokenizer.add_special_tokens({'additional_special_tokens': mem_tokens}) 
+        self.tokenizer.mem_tokens = mem_tokens
+        self.tokenizer.mem_token_ids = [self.tokenizer.convert_tokens_to_ids(elt) for elt in self.tokenizer.mem_tokens]
+        self.tokenizer.mem_token_ids_pt = torch.LongTensor(self.tokenizer.mem_token_ids)
+        self.model.resize_token_embeddings(len(self.tokenizer))
+            
+        if self.tokenizer.pad_token_id is None:
+            self.tokenizer.pad_token_id = self.tokenizer.bos_token_id
+            
+        if not use_mlp:
+            assert decoder_hidden_size == self.hidden_size, f'Mlp mandatory is hidden sizes not equal: {decoder_hidden_size} vs {self.hidden_size}'
+            
+        self.lora = False
+        self.lora_name = 'compr_adapter'
+        
+    def prepare_mem_tokens_optimization(self):
+        assert self.lora, 'should only be called with lora.'
+        self.model.get_input_embeddings().weight.requires_grad = True
+        # Applying a hook zero-ing the gradients except for the mem token:
+        def hook(grad):
+            mask = torch.zeros_like(grad)
+            mask[self.tokenizer.mem_token_ids] = 1.0
+            return grad * mask
+        self.model.get_input_embeddings().weight.register_hook(hook)            
+        
+    def set_lora(self, peft_config):
+        self.model.add_adapter(peft_config, self.lora_name)
+        self.model.set_adapter(self.lora_name)
+        self.lora = True
+        self.prepare_mem_tokens_optimization()
+
+    def forward(self, input_ids, attention_mask):
+        assert input_ids.size() == attention_mask.size()
+        assert len(input_ids.size()) == 2
+        
+        batch_size_times_top_k = input_ids.size(0)
+        
+        last_hidden_states = self.model(input_ids=input_ids,
+                                        attention_mask=attention_mask, 
+                                        output_hidden_states=True).hidden_states[-1]
+        
+        # Getting the hidden states at the mem token positions, as for regular cocom:
+        mask = torch.isin(input_ids, self.tokenizer.mem_token_ids_pt.to(input_ids.device))
+        selected_n_tokens = last_hidden_states[mask].reshape(last_hidden_states.size(0), -1, last_hidden_states.size(-1))            
+        
+        assert selected_n_tokens.size() == (batch_size_times_top_k, self.n_emb, self.hidden_size), f"{selected_n_tokens.size()} vs {(batch_size_times_top_k, self.n_emb, self.hidden_size)}"
+        
+        if self.use_mlp:
+            selected_n_tokens = self.mlp(selected_n_tokens) # now of shape (batch_size, top_k, decoder_hidden_size)
+            
+        assert selected_n_tokens.size() == (batch_size_times_top_k, self.n_emb, self.decoder_hidden_size), f"{selected_n_tokens.size()} vs {(batch_size_times_top_k, self.n_emb, self.decoder_hidden_size)}"
+        
+        return selected_n_tokens
+    
+    def get_lora_path_from_directory(self, directory):
+        return os.path.join(directory, 'compressor_adapters.pth')
+    
+    def get_compressor_path_from_directory(self, directory):
+        return os.path.join(directory, 'compressor.pth')
+    
+    def get_mlp_path_from_directory(self, directory):
+        return os.path.join(directory, 'mlp.pth')
+    
+    def get_first_layer_path_from_directory(self, directory):
+        return os.path.join(directory, 'first_layer.pth')
+    
+    def get_first_layer_state_dict(self) -> dict:
+        out = {}
+        for k, v in self.model.named_parameters():
+            if 'embed_tokens.weight' in k:
+                out[k] = v.cpu()
+                
+        assert len(out) == 1, len(out) # We should get exactly one layer here
+        return out
+    
+    def save_pretrained(self, save_directory):
+        """
+        Here we just save mlp state_dict and model state_dict
+        Config is handled in cocom model.
+        """
+        if not os.path.exists(save_directory):
+            os.makedirs(save_directory)
+        
+        # Save MLP weights
+        if self.use_mlp:
+            mlp_path = self.get_mlp_path_from_directory(directory=save_directory)
+            torch.save(self.mlp.state_dict(), mlp_path)
+        
+        # Saving the model
+        if not self.lora: # full training: save the full dict:
+            model_path = self.get_compressor_path_from_directory(directory=save_directory)
+            torch.save(self.model.state_dict(), model_path)
+        else: # lora training of the compressor
+            # We save the first layer:
+            first_layer_state_dict = self.get_first_layer_state_dict()
+            torch.save(first_layer_state_dict, self.get_first_layer_path_from_directory(directory=save_directory))
+            
+            # We save the adapters:
+            adapter_state_dict = {k: v.cpu() for k, v in self.model.get_adapter_state_dict(self.lora_name).items()}
+            torch.save(adapter_state_dict, self.get_lora_path_from_directory(directory=save_directory))
+            
+    def load_adapter(self, load_directory, peft_config):    
+        assert peft_config is not None
+        map_location = torch.device("cpu") if not torch.cuda.is_available else None
+        adapter_state_dict = torch.load(self.get_lora_path_from_directory(directory=load_directory), map_location=map_location, weights_only=True)
+        print('loading compr adapter onto compressor model from', self.get_lora_path_from_directory(directory=load_directory))
+        self.model.load_adapter(peft_config=peft_config, adapter_name=self.lora_name, adapter_state_dict=adapter_state_dict)
+        self.lora = True
+        self.prepare_mem_tokens_optimization()
+        
+    def load_first_layer(self, load_directory):
+        map_location = torch.device("cpu") if not torch.cuda.is_available else None
+        first_layer_state_dict = torch.load(self.get_first_layer_path_from_directory(load_directory), map_location=map_location, weights_only=True)
+        assert len(first_layer_state_dict.keys()) == 1
+        self.model.load_state_dict(first_layer_state_dict, strict=False)
+
+    def load_pretrained(self, load_directory, lora: bool = False, peft_config=None):
+        """
+        Loading the state dicts.
+        :lora: if True then the compressor was trained using lora: we just need to load the adapters
+        if False, the compressor was fully trained: we load it fully.
+        """
+        if self.use_mlp:
+            mlp_path = self.get_mlp_path_from_directory(directory=load_directory)
+            self.mlp.load_state_dict(torch.load(mlp_path, weights_only=True))
+        
+        if lora:
+            self.load_first_layer(load_directory)
+            self.load_adapter(load_directory, peft_config)
+            
+        else:
+            model_path = self.get_compressor_path_from_directory(directory=load_directory)
+            self.model.load_state_dict(torch.load(model_path, weights_only=True))  
+            
+    def prepare_inputs(self, texts, max_length, q_texts=None):
+        if q_texts is not None: # Query-dependent here:
+            assert len(texts) == len(q_texts), f"{len(texts)} == {len(q_texts)}"
+            if self.compr_model_name == 'mistral_trimmed':
+                # No special token, just formulating:
+                texts_to_encode = [ '\nQuery:\n' + query + 'Document:\n' + text for text, query in zip(texts, q_texts)]
+                inp_enc = self.tokenizer(texts_to_encode, 
+                                        return_tensors='pt', 
+                                        padding='max_length', 
+                                        max_length=max_length + 8, # some margin for query/doc stuff + bos / eos
+                                        truncation=True,
+                                        add_special_tokens=True)
+            else:
+                inp_enc = self.tokenizer(q_texts,  # we put the query in first position
+                                        texts, 
+                                        return_tensors='pt', 
+                                        padding='max_length', 
+                                        max_length=max_length + 3,
+                                        truncation='only_second',
+                                        add_special_tokens=True)
+        else:
+            inp_enc = self.tokenizer(texts, return_tensors='pt', padding='max_length', max_length=max_length + 2, truncation=True, add_special_tokens=True)
+            
+        inp_enc['input_ids'], inp_enc['attention_mask'] = add_memory_tokens_to_inputs(inp_enc['input_ids'], 
+                                                                                        inp_enc['attention_mask'], 
+                                                                                        self.n_emb, 
+                                                                                        tokenizer=self.tokenizer)
+            
+        return inp_enc
+
+
+def add_memory_tokens_to_inputs(input_ids: torch.Tensor, attention_mask: torch.Tensor, n_mem_tokens: int, tokenizer):
+    """
+    Concatenate the input ids with n_mem_tokens mem_tokens and update the corresponding attention mask
+    """
+    assert len(tokenizer.mem_tokens) == n_mem_tokens, f"{len(tokenizer.mem_tokens)} VS {n_mem_tokens}"
+    mem_tokens = torch.stack([tokenizer.mem_token_ids_pt] * input_ids.size(0), 0)
+    assert len(mem_tokens.size()) == 2
+    assert len(mem_tokens) == input_ids.size(0)
+    assert len(mem_tokens[0]) == n_mem_tokens
+    #mem_tokens = torch.full((input_ids.size(0), n_mem_tokens), tokenizer.mem_token_id, dtype=torch.long)
+    input_ids = torch.cat([input_ids, mem_tokens], dim=1)
+    attention_mask = torch.cat([attention_mask, torch.ones(input_ids.size(0), n_mem_tokens)], dim=1)
+    return input_ids, attention_mask
+
+
+class COCOMConfig(PretrainedConfig):
+
+    model_type = "COCOM"
+    def __init__(self,
+                decoder_model_name: str = "meta-llama/Llama-2-7b-chat-hf",
+                doc_max_length: int = 128,
+                quantization: str = 'no',
+                sep: bool = False,
+                compr_model_name: str = "google-bert/bert-base-uncased",
+                compr_rate: int = 64,
+                compr_n_layers: int = None, # only for surgical mistral compressor
+                compr_every_n_layer: int = None,
+                compr_base_model_name: str = 'mistralai/Mistral-7B-Instruct-v0.2',
+                compr_rms_norm: bool = False, # only for surgical mistral compressor: if true, rms norm applied on h-s
+                compr_mlp_hidden_dim: int = 8096,
+                compr_use_mlp: bool = True, 
+                lora: bool = False, # lora on decoder (and decoder as compr)
+                lora_compressor: bool = False, # lora only on the compressor if it exists
+                training_form: str = "both",
+                lora_r: int = 16,
+                lora_r_compressor: int = None,
+                load_adapters: bool = True,
+                kbtc_training: bool = False,
+                optimize_mem_tokens: bool = False,
+                different_mem_tokens: bool = False,
+                attn_implementation: str = 'flash_attention_2',
+                device_map = None,
+                **kwargs):
+        super().__init__(**kwargs)
+
+        self.decoder_model_name = decoder_model_name # model name of decoder
+        self.doc_max_length = doc_max_length # the maximum length of document that can be used by this model (it is used to compute number of mem tokens !)
+        self.quantization = quantization # quantization, could be no, int4, int8
+        self.sep = sep # boolean type, whether to use sep token
+        
+        self.compr_model_name = compr_model_name # model name of compressor
+        self.compr_rate = compr_rate # compression rate
+        self.compr_use_mlp = compr_use_mlp
+        self.compr_mlp_hidden_dim = compr_mlp_hidden_dim
+        self.compr_n_layers = compr_n_layers
+        self.compr_every_n_layer = compr_every_n_layer
+        self.compr_base_model_name = compr_base_model_name
+        self.compr_rms_norm = compr_rms_norm
+        
+        self.lora = lora # boolean type, whether to use lora trsining
+        self.lora_compressor = lora_compressor
+        self.training_form = training_form # training form, could be compressor: training only comprssor; both: training both
+        # Or both_separately: training both with separate adapters
+        self.lora_r = lora_r # lora_r for lora training, we use 16 throughout the experiment.
+        self.lora_r_compressor = lora_r_compressor or lora_r # defaulting to same lora as decoder.
+        self.load_adapters = load_adapters # used to load pretrained model: we first load without adapters, and then load them from file.
+        self.optimize_mem_tokens = optimize_mem_tokens
+        self.different_mem_tokens = different_mem_tokens
+        
+        self.kbtc_training = kbtc_training
+        
+        self.device_map = device_map
+        
+        self.attn_implementation = attn_implementation
+        
+        if training_form == 'compressor':
+            assert compr_model_name is not None and not self.lora
+            
+        
+class COCOM(PreTrainedModel):
+    config_class = COCOMConfig
+    def __init__(self, cfg):
+        super().__init__(cfg)
+        self.decoder_model_name = cfg.decoder_model_name
+        self.decoder = self.create_decoder(cfg)
+        
+        self.doc_max_length = cfg.doc_max_length
+        
+        print('Base decoder nb parameters', self.decoder.num_parameters())
+
+        self.compr_model_name = cfg.compr_model_name
+        self.training_form = cfg.training_form
+        self.lora = cfg.lora
+        self.adapter_keys = []
+
+        self.compr = None
+        # when compr_model_name is not set, then means using a decoder-based compressor, otherwise a bert based compressor
+        if cfg.compr_model_name is not None:
+            # case bert based compressor
+            print('Instantiating compressor ', cfg.compr_model_name)
+            self.compr = BertCompressor(cfg.compr_model_name, 
+                                        cfg.compr_rate, 
+                                        doc_max_length=self.doc_max_length,
+                                        decoder_hidden_size=self.decoder.config.hidden_size,
+                                        mlp_hidden_dim=cfg.compr_mlp_hidden_dim,
+                                        compr_n_layers=cfg.compr_n_layers,
+                                        compr_every_n_layer=cfg.compr_every_n_layer,
+                                        compr_base_model_name=cfg.compr_base_model_name,
+                                        compr_rms_norm=cfg.compr_rms_norm,
+                                        use_mlp=cfg.compr_use_mlp,
+                                        attn_implementation=cfg.attn_implementation)
+
+        # set lora adaptors on decoder model
+        if cfg.lora:
+            peft_config = self.get_peft_config(lora_r=cfg.lora_r)
+
+            if cfg.load_adapters:
+                self.decoder.add_adapter(peft_config, 'decoder_adapter')
+                self.decoder.set_adapter('decoder_adapter') # active adapter by default
+                self.adapter_keys.append('decoder_adapter')
+
+            # Create separate adapters (if not BERT compressor and training_form == 'both_separately')
+            if self.training_form == 'both_separately' and self.compr is None:
+                if cfg.load_adapters:
+                    self.decoder.add_adapter(peft_config, 'encoder_adapter')
+                    self.adapter_keys.append('encoder_adapter')
+                    
+        # set lora adapters on compressor model:
+        if cfg.lora_compressor and self.compr is not None and cfg.load_adapters:
+            peft_config = self.get_peft_config(lora_r=cfg.lora_r_compressor)
+            self.compr.set_lora(peft_config)
+                    
+        self.decoder_tokenizer = COCOM.create_decoder_tokenizer(cfg)
+
+        # resize the tokenizer embedding
+        self.decoder.resize_token_embeddings(len(self.decoder_tokenizer))
+        self.decoder.generation_config.top_p = None
+        self.decoder.generation_config.temperature = None
+        self.decoder.generation_config.pad_token_id = self.decoder_tokenizer.pad_token_id
+        
+        # self.decoder.gradient_checkpointing_enable()
+        # if self.compr is not None:
+        #     self.compr.gradient_checkpointing_enable()
+
+        # other settings
+        self.generation_top_k = 1
+        self.sep = cfg.sep
+        self.compr_rate = cfg.compr_rate
+        self.local_rank = os.getenv('LOCAL_RANK', '0')
+        
+        self.n_mem_tokens = self.doc_max_length // self.compr_rate # crucial!
+
+
+        if self.lora:
+            for adapter_key in self.adapter_keys:
+                self.decoder.set_adapter(adapter_key)
+                print(f'Adapter {adapter_key} trainable parameters: {self.num_parameters(only_trainable=True)}')
+                
+            #  We need to activate all adapters so that they are both trained...
+            self.set_all_adapters()
+        else:
+            print(f'Total trainable parameters: {self.num_parameters(only_trainable=True)}')
+            
+        if self.compr is not None:
+            print(f'Compressor number of parameters: {self.compr.model.num_parameters(only_trainable=True)}')
+            
+        self.prepare_mem_tokens_optimization()
+            
+    def prepare_mem_tokens_optimization(self):
+        if self.config.optimize_mem_tokens:
+            if self.compr is None:
+                # Enforcing gradients for input embeddings (even if lora)
+                self.decoder.get_input_embeddings().weight.requires_grad = True
+                # Applying a hook zero-ing the gradients except for the mem token:
+                def hook(grad):
+                    mask = torch.zeros_like(grad)
+                    mask[self.decoder_tokenizer.mem_token_ids] = 1.0
+                    return grad * mask
+                self.decoder.get_input_embeddings().weight.register_hook(hook)
+                
+    def set_all_adapters(self):
+        if len(self.adapter_keys) > 0:
+            self.decoder.set_adapter(self.adapter_keys)
+            
+    @staticmethod
+    def create_decoder_tokenizer(cfg: COCOMConfig):
+        decoder_tokenizer = AutoTokenizer.from_pretrained(cfg.decoder_model_name, use_fast=True, padding_side='left')
+
+        # define special tokens
+        n_mem_tokens = cfg.doc_max_length // cfg.compr_rate
+        if cfg.different_mem_tokens:
+            # estimation fo the number of memory tokens needed:
+            mem_tokens = ['<MEM' + str(i) + '>' for i in range(n_mem_tokens)]
+            decoder_tokenizer.add_special_tokens({'additional_special_tokens': mem_tokens + ['<AE>', '<ENC>', '<SEP>']}) 
+            decoder_tokenizer.mem_tokens = mem_tokens
+        else:
+            decoder_tokenizer.add_special_tokens({'additional_special_tokens': ['<MEM>', '<AE>', '<ENC>', '<SEP>']})
+            decoder_tokenizer.mem_tokens = ['<MEM>'] * n_mem_tokens
+        
+        decoder_tokenizer.mem_token_ids = [decoder_tokenizer.convert_tokens_to_ids(elt) for elt in decoder_tokenizer.mem_tokens]
+        decoder_tokenizer.mem_token_ids_pt = torch.LongTensor(decoder_tokenizer.mem_token_ids) # required later on for operations on tensors
+        
+        decoder_tokenizer.ae_token = '<AE>' # token for autoencoding on decoder side
+        decoder_tokenizer.ae_token_id = decoder_tokenizer.convert_tokens_to_ids('<AE>')
+        decoder_tokenizer.enc_token = '<ENC>' # token for autoencoding on compressor side
+        decoder_tokenizer.sep_token = '<SEP>' # sep token between document
+        decoder_tokenizer.sep_token_id = decoder_tokenizer.convert_tokens_to_ids('<SEP>')
+
+        # If kbtc training, we add another one yet
+        if cfg.kbtc_training:
+            decoder_tokenizer.add_special_tokens({'additional_special_tokens': ['<KBTC>']})
+            decoder_tokenizer.kbtc_token = '<KBTC>'
+            decoder_tokenizer.kbtc_token_id = decoder_tokenizer.convert_tokens_to_ids('<KBTC>')
+
+        # if pad token exists then use pad token, othrwise bos token
+        if decoder_tokenizer.pad_token_id is None:
+            decoder_tokenizer.pad_token_id = decoder_tokenizer.bos_token_id
+
+        return decoder_tokenizer
+
+    def get_peft_config(self, lora_r: int) -> LoraConfig:
+        """
+        Builds the peft config
+        """
+        return LoraConfig(task_type="CAUSAL_LM", r=lora_r, lora_alpha=2*lora_r, target_modules='all-linear', lora_dropout=0.1)
+
+    def create_decoder(self, cfg):
+        """
+        Loads the base decoder.
+        """
+        if torch.cuda.is_available():
+            if cfg.quantization == "no":
+                return AutoModelForCausalLM.from_pretrained(
+                    cfg.decoder_model_name,
+                    torch_dtype=torch.bfloat16,
+                    attn_implementation=self.config.attn_implementation,
+                    # low_cpu_mem_usage = True,
+                    device_map=cfg.device_map
+                    )
+            elif cfg.quantization == "int4":
+                quant_config = BitsAndBytesConfig(
+                    load_in_4bit=True,
+                    bnb_4bit_quant_type='nf4',
+                    bnb_4bit_compute_dtype='bfloat16',
+                    # low_cpu_mem_usage = True,
+                )
+                return AutoModelForCausalLM.from_pretrained(
+                    cfg.decoder_model_name,
+                    quantization_config=quant_config,
+                    attn_implementation=self.config.attn_implementation,
+                    torch_dtype=torch.bfloat16,
+                    resume_download=True,
+                    # low_cpu_mem_usage = True,
+                    trust_remote_code=True,
+                    device_map=cfg.device_map
+                )
+            elif cfg.quantization == "int8":
+                quant_config = BitsAndBytesConfig(
+                    load_in_8bit=True,
+                    llm_int8_enable_fp32_cpu_offload=True,
+                    bnb_4bit_compute_dtype='bfloat16',
+                    # low_cpu_mem_usage = True,
+                )
+                return AutoModelForCausalLM.from_pretrained(
+                    cfg.decoder_model_name,
+                    quantization_config=quant_config,
+                    attn_implementation=self.config.attn_implementation,
+                    torch_dtype=torch.bfloat16,
+                    resume_download=True,
+                    # low_cpu_mem_usage = True,
+                    trust_remote_code=True,
+                    device_map=cfg.device_map
+                )
+            else:
+                raise NotImplementedError()
+        else:
+            return AutoModelForCausalLM.from_pretrained(
+                cfg.decoder_model_name,
+                torch_dtype=torch.bfloat16,
+                resume_download=True,
+                # low_cpu_mem_usage = True,
+                trust_remote_code=True,
+                device_map=cfg.device_map
+            )
+            
+    def compress(self, enc_input_ids, enc_attention_mask):
+        if self.compr:
+            return self.compr(enc_input_ids, enc_attention_mask)
+        else:
+            return self.compr_decoder(enc_input_ids, enc_attention_mask)
+
+    def replace_emb(self, compressed_embs, dec_input_ids):
+        """
+        Compression logic (either with decoder or with dedicated compressor)
+        """
+        indices = range(0, compressed_embs.size(0) + 1, self.generation_top_k)            
+        input_embeds = self.replace_embeddings(compressed_embs, dec_input_ids, indices)
+        return input_embeds
+
+    def compr_decoder(self, input_ids, attention_mask):
+        """
+        Compression using the decoder
+        """
+        assert input_ids.size() == attention_mask.size(), f"{input_ids.size()} vs {attention_mask.size()}"
+        
+        # Switch adapter if we are training two different ones:
+        if 'encoder_adapter' in self.adapter_keys:
+            self.decoder.set_adapter('encoder_adapter')
+
+        emb = self.decoder(input_ids=input_ids,
+                           attention_mask=attention_mask,
+                           output_hidden_states=True).hidden_states[-1]
+        mask = torch.isin(input_ids, self.decoder_tokenizer.mem_token_ids_pt.to(input_ids.device))
+        return emb[mask].reshape(emb.size(0), -1, emb.size(-1))
+    
+    def prepare_encoder_inputs_to_decoder(self, texts, max_length, q_texts=None):
+        if q_texts is not None:
+            texts_to_encode = [self.decoder_tokenizer.enc_token + self.decoder_tokenizer.bos_token + '\nQuery:\n' + query + 'Document:\n' + text + self.decoder_tokenizer.eos_token 
+                               for text, query in zip(texts, q_texts)]
+            inp_enc = self.decoder_tokenizer(texts_to_encode, return_tensors='pt', padding='max_length', max_length=max_length + 8, truncation=True, add_special_tokens=False)
+        else:
+            inp_enc = [self.decoder_tokenizer.enc_token + self.decoder_tokenizer.bos_token + text + self.decoder_tokenizer.eos_token for text in texts]
+            inp_enc = self.decoder_tokenizer(inp_enc, return_tensors='pt', padding="max_length", max_length=max_length+3, truncation=True, add_special_tokens=False)
+            
+        num_mem_tokens = self.doc_max_length // self.compr_rate
+        assert num_mem_tokens == len(self.decoder_tokenizer.mem_tokens)
+        inp_enc['input_ids'], inp_enc['attention_mask'] = add_memory_tokens_to_inputs(inp_enc['input_ids'], 
+                                                                                        inp_enc['attention_mask'], 
+                                                                                        num_mem_tokens, 
+                                                                                        tokenizer=self.decoder_tokenizer)
+        
+        return inp_enc
+    
+    def prepare_encoder_inputs(self, texts: list[str], max_length: int, q_texts: list[str] = None):
+        """
+        Create the inputs to the encoder, for compression.
+        """
+        if q_texts is not None:
+            assert len(texts) == len(q_texts), f"{len(texts)} == {len(q_texts)}"
+
+        # Case where the encoder is the decoder with adapter:
+        if self.compr is None:
+            return self.prepare_encoder_inputs_to_decoder(texts, max_length, q_texts)
+        
+        # Case where the encoder is a separate network:
+        else:
+            return self.compr.prepare_inputs(texts, max_length, q_texts)
+
+    def replace_embeddings(self, compressed_embs, dec_input_ids, indices):
+        """
+        Replace memory tokens in the decoder input to with the compressed embeddings
+        """
+        inputs_embeds = self.decoder.get_input_embeddings()(dec_input_ids)
+        num_embs = compressed_embs.size(1)
+        if self.sep:
+            slot_len = num_embs + 1
+        else:
+            slot_len = num_embs
+        # get first mem_token indices
+        first_mem_token_indices = torch.argmax((dec_input_ids == self.decoder_tokenizer.mem_token_ids[0]).int(), dim=1)
+        batch_size = inputs_embeds.size(0)
+        # for each example in batch, replace them with compressed embeddings
+        for i in range(batch_size):
+            for j in range(indices[i], indices[i + 1]):
+                start_idx = first_mem_token_indices[i].item() + (j-indices[i]) * slot_len
+                assert inputs_embeds[i, start_idx:start_idx + num_embs, :].size() == compressed_embs[j].size(), \
+                    f"{inputs_embeds[i, start_idx:start_idx + num_embs, :].size()} VS {compressed_embs[j].size()}"
+                inputs_embeds[i, start_idx:start_idx + num_embs, :] = compressed_embs[j]
+        return inputs_embeds
+
+    def forward(self,
+                enc_input_ids: torch.LongTensor = None,
+                enc_attention_mask: torch.LongTensor = None,
+                dec_input_ids: torch.LongTensor = None,
+                dec_attention_mask: torch.LongTensor = None,
+                labels: torch.LongTensor = None):
+        """
+        enc_input_ids: stores the contexts, should be flattened from all queries before input, can be of shape:
+            - (batch_size*generation_top_k, enc_token_length)
+            - (batch_size, generation_top_k, enc_token_length)
+        enc_attention_mask: attention mask of enc_input_ids, same shape as enc_input_ids
+        dec_input_ids: stores the prompts (including mem tokens), dimention (batch_size, dec_token_length)
+        dec_attention_mask: attention mask of dec_input_ids
+        """ 
+        assert enc_input_ids.size() == enc_attention_mask.size(), f"{enc_input_ids.size()} vs {enc_attention_mask.size()}"
+        
+        if len(enc_input_ids.size()) == 3: # likely from bergen: we just flatten all of this to perform encoding in one batch
+            batch_size, top_k, seq_length = enc_input_ids.size()
+            enc_input_ids = enc_input_ids.view(batch_size * top_k, seq_length)
+            enc_attention_mask = enc_attention_mask.view(batch_size * top_k, seq_length)
+        
+        # Here, we should have top_k times more elements in enc_input_ids than in dec_input_ids
+        assert enc_input_ids.size(0) == dec_input_ids.size(0) * self.generation_top_k, \
+            f"{enc_input_ids.size(0)} VS {dec_input_ids.size(0)} with generation_top_k={self.generation_top_k}"
+            
+        # Perform compression with gradient tracking
+        compressed_embs = self.compress(enc_input_ids, enc_attention_mask)
+        inputs_embeds = self.replace_emb(compressed_embs, dec_input_ids)
+
+        # if training_form is compressor, then detach the inputs_embeds, to make gradient not count in decoder
+        if (self.training_form == "compressor") and (self.compr is None):
+            inputs_embeds  = inputs_embeds.detach()
+
+        # decoding
+        if 'decoder_adapter' in self.adapter_keys:
+            self.decoder.set_adapter('decoder_adapter')
+
+        decoder_outputs = self.decoder(inputs_embeds=inputs_embeds, attention_mask=dec_attention_mask, labels=labels)
+
+        # At end of forward, we need to activate all adapters so that they are both trained...
+        self.set_all_adapters()
+
+        return {"loss": decoder_outputs.loss, "logits": decoder_outputs.logits}
+
+    def generate(self, model_input, max_new_tokens=128, return_doc_embeddings: bool = False):
+
+        enc_input_ids, enc_attention_mask, dec_input_ids, dec_attention_mask = model_input['enc_input_ids'], model_input['enc_attention_mask'], model_input['dec_input_ids'], model_input['dec_attention_mask']
+        
+        assert enc_input_ids.size() == enc_attention_mask.size()
+        
+        if len(enc_input_ids.size()) == 3: # likely from bergen: we just flatten all of this to perform encoding in one batch
+            batch_size, top_k, seq_length = enc_input_ids.size()
+            enc_input_ids = enc_input_ids.view(batch_size * top_k, seq_length)
+            enc_attention_mask = enc_attention_mask.view(batch_size * top_k, seq_length)
+            
+        # Here, we should have top_k times more elements in enc_input_ids than in dec_input_ids
+        assert enc_input_ids.size(0) == dec_input_ids.size(0) * self.generation_top_k, \
+            f"{enc_input_ids.size(0)} VS {dec_input_ids.size(0)} with generation_top_k={self.generation_top_k}"
+            
+        compressed_embs = self.compress(enc_input_ids.to('cuda'), enc_attention_mask.to('cuda'))
+        inputs_embeds = self.replace_emb(compressed_embs, dec_input_ids.to('cuda'))
+        
+        # Switch adapter if we are training two different ones:
+        if 'decoder_adapter' in self.adapter_keys:
+            self.decoder.set_adapter('decoder_adapter') 
+
+        output_ids = self.decoder.generate(
+            inputs_embeds=inputs_embeds.to("cuda"),
+            attention_mask=dec_attention_mask.to("cuda"),
+            do_sample=False,
+            top_p=None,
+            max_new_tokens=max_new_tokens
+            )
+
+        decoded = self.decoder_tokenizer.batch_decode(output_ids, skip_special_tokens=True)
+        
+        if return_doc_embeddings:
+            # Compressed_embds is of shape (batch_size*top_k, n_mem_tokens, hidden_dim)
+            # We reshape to batch_size, top_k, n_mem_tokens, hidden_dim
+            assert batch_size is not None
+            assert top_k is not None
+            compressed_embs = compressed_embs.view(batch_size, top_k, compressed_embs.size(1), compressed_embs.size(2))
+            return decoded, compressed_embs
+        else:
+            return decoded
+
+    def get_all_adapters_state_dict(self):
+        """
+        Return the state dicts of the adapters
+        Used for saving so we go to cpu automatically
+        """
+        return {key: {k:v.cpu() for k, v in self.decoder.get_adapter_state_dict(key).items()} for key in self.adapter_keys}
+
+    def load_adapter_from_state_dict(self, peft_config: LoraConfig, adapter_name: str, adapter_state_dict: dict) -> None:
+        """
+        Creates an adapter from the state dict (used to load from pretrained)
+        """
+        # assert adapter_name not in self.adapter_keys, f'Adapter {adapter_name} already exists'
+        print(f'loading adapter {adapter_name}')
+        self.decoder.load_adapter(peft_config=peft_config, adapter_name=adapter_name, adapter_state_dict=adapter_state_dict)
+        self.adapter_keys.append(adapter_name)
+        
+    def get_decoder_first_and_last_layer_state_dict(self) -> dict:
+        """
+        Just getting the first and last layers: the only ones which change when adding tokens
+        Used to save the model so we automatically move to cpu.
+        """
+        out = {}
+        for k, v in self.decoder.named_parameters():
+            if 'lm_head.weight' in k or 'embed_tokens.weight' in k:
+                out[k] = v.cpu()
+                
+        # assert len(out) == 2, len(out) # We should get both the embedding layer and the head layer.
+        return out
+
+    def save_pretrained(self, save_directory: str, **kwargs):
+        """
+        Save only the LoRA adapters and their configurations.
+        """
+        if self.lora:
+            if not os.path.exists(save_directory):
+                os.makedirs(save_directory) 
+
+            # Save the LoRA adapter weights
+            torch.save(self.get_all_adapters_state_dict(), os.path.join(save_directory, "adapters.pth"))
+            
+            # Save the first and last layers of decoder (because of diffs with tokens !)
+            torch.save(self.get_decoder_first_and_last_layer_state_dict(), os.path.join(save_directory, "decoder_first_last_layers.pth"))
+            
+            # Save the bert compressor if it exists
+            if self.compr_model_name is not None:
+                self.compr.save_pretrained(os.path.join(save_directory, 'compressor'))
+
+            # Save the configuration
+            self.config.save_pretrained(save_directory)
+        else:
+            super().save_pretrained(save_directory, **kwargs)
+
+    @classmethod
+    def from_pretrained(cls, pretrained_model_name_or_path, *args, **kwargs):
+        """
+        Loading: to take care of checkpoints containing only lora and not base model.
+        """
+        # Load the configuration
+        config = COCOMConfig.from_pretrained(pretrained_model_name_or_path)
+        
+        config.attn_implementation = kwargs.get('attn_implementation', config.attn_implementation)  
+        
+        map_location = torch.device("cpu") if not torch.cuda.is_available() else None
+
+        if config.lora:
+            # We need to delay the construction of the adapters (otherwise peft complains)
+            config.load_adapters = False
+
+            if 'device_map' in kwargs:
+                config.device_map = kwargs['device_map']
+
+            # Initialize the model
+            model = cls(config)
+                    
+            # Loading first and last layers (they might have changed due to extra tokens)
+            first_and_last_layers_path = get_local_file_path(pretrained_model_name_or_path, "decoder_first_last_layers.pth")
+            
+            if os.path.exists(first_and_last_layers_path):
+                first_and_last_decoder_state_dict = torch.load(first_and_last_layers_path, map_location=map_location, weights_only=True)
+                for key in first_and_last_decoder_state_dict:
+                    assert key in model.decoder.state_dict()
+                    model.decoder.load_state_dict(first_and_last_decoder_state_dict, strict=False)
+
+            else:
+                print('FIRST AND LAST LAYER NOT FOUND (ok for some old models):', first_and_last_layers_path)
+                
+            peft_config = model.get_peft_config(lora_r=config.lora_r)
+            
+            adapters_path = get_local_file_path(pretrained_model_name_or_path, "adapters.pth")
+
+            if os.path.exists(adapters_path):
+                adapters_state_dict = torch.load(adapters_path, map_location=map_location, weights_only=True)
+            
+                for key, val in adapters_state_dict.items():
+                    model.load_adapter_from_state_dict(peft_config=peft_config, adapter_name=key, adapter_state_dict=val)
+                    
+            else:
+                warnings.warn(f'I see lora on that PISCO model, but {adapters_path} does not exist, it may be normal \
+                        for recent versions of transformers, be aware.')
+
+            # If there is a compressor, it's been built: we just need to load the state dict or the adapters:
+            if config.compr_model_name is not None:
+                compressor_mlp_path = get_local_file_path(pretrained_model_name_or_path, "compressor/mlp.pth")
+                compressor_compressor_path = get_local_file_path(pretrained_model_name_or_path, "compressor/compressor.pth")
+                model.compr.load_pretrained(os.path.dirname(compressor_mlp_path), 
+                                            lora=config.lora_compressor, 
+                                            peft_config=model.get_peft_config(lora_r=config.lora_r_compressor))
+
+            model.set_all_adapters()
+            model.config.load_adapters = True
+            return model
+
+        else:
+            return super().from_pretrained(pretrained_model_name_or_path, **kwargs)
+        
+    def generate_from_text(self, questions: list[str], documents: list[list[str]], max_new_tokens: int = 128, query_dependent: bool = False) -> list[str]:
+        """
+        Generates answers from documents (via compression then decoding)
+        questions: list of string
+        documents: list of list of strings (they should all be of equal length: the nb of doc for each question)
+        query_dependent: if true then the compression is done query-dependently
+        """
+        self.generation_top_k = len(documents[0])
+        assert len(documents) == len(questions)
+        assert all([len(context) == len(documents[0]) for context in documents])
+        flat_documents = sum(documents, [])
+        
+        model_input = {}
+        
+        # Creating encoder inputs:
+        if query_dependent:
+            # We provide the question for compression:
+            input_encoder = self.prepare_encoder_inputs(flat_documents, max_length=128, q_texts=questions)
+        else:
+            input_encoder = self.prepare_encoder_inputs(flat_documents, max_length=128)
+            
+        device = self.decoder.device
+        model_input['enc_input_ids'], model_input['enc_attention_mask'] = input_encoder['input_ids'].to(device), input_encoder['attention_mask'].to(device)
+        
+        # Creating decoder inputs
+        instr = [self.blend_prompt_and_memory_tokens(query=q) for q in questions]
+        inp_dec = self.decoder_tokenizer(instr, return_tensors='pt', padding="longest", add_special_tokens=False, truncation=True,  max_length=2048)
+        model_input['dec_input_ids'], model_input['dec_attention_mask'] = inp_dec['input_ids'].to(device), inp_dec['attention_mask'].to(device)
+        
+        # Generation
+        return self.generate(model_input, max_new_tokens=max_new_tokens)
+    
+    def generate_from_compressed_documents_and_questions(self, questions: list[str], compressed_documents: torch.Tensor, max_new_tokens: int = 128) -> list[str]:
+        """
+        Generates answers from compressed documents
+        questions: list of string
+        compressed_documents: torch tensor, its first dimension should be a multiple of len(questions)
+        """
+        self.generation_top_k = compressed_documents.size(0) // len(questions)
+        assert compressed_documents.size(0) % self.generation_top_k == 0, f"{compressed_documents.size(0)} {self.generation_top_k}"
+        
+        # Creating decoder inputs
+        instr = [self.blend_prompt_and_memory_tokens(query=q) for q in questions]
+        inp_dec = self.decoder_tokenizer(instr, return_tensors='pt', padding="longest", add_special_tokens=False, truncation=True,  max_length=2048)
+        device = self.decoder.device
+        dec_input_ids, dec_attention_mask = inp_dec['input_ids'].to(device), inp_dec['attention_mask'].to(device)
+
+        # Creating input decoder embeddings from prompt + compressed documents
+        inputs_embeds = self.replace_emb(compressed_documents, dec_input_ids)
+        
+        # Activating decoder generator:
+        if 'decoder_adapter' in self.adapter_keys:
+            self.decoder.set_adapter('decoder_adapter')
+            
+        output_ids = self.decoder.generate(
+            inputs_embeds=inputs_embeds,
+            attention_mask=dec_attention_mask,
+            generation_config=self.generation_config,
+            max_new_tokens=max_new_tokens
+            )
+        
+        # de-tokenizing
+        return self.decoder_tokenizer.batch_decode(output_ids, skip_special_tokens=True)
+        
+    def compress_documents(self, documents: list[str], questions: list[str] = None) -> torch.Tensor:
+        """
+        Compress a list of documents
+        if questions is not None, assumes compression is done query-dependently !
+        """
+        if questions is None:
+            input_encoder = self.prepare_encoder_inputs(documents, max_length=128)
+        else:
+            input_encoder = self.prepare_encoder_inputs(documents, max_length=128, q_texts=questions)
+        enc_input_ids = input_encoder['input_ids'].to(self.decoder.device)
+        attention_mask = input_encoder['attention_mask'].to(self.decoder.device)
+        return self.compress(enc_input_ids=enc_input_ids, enc_attention_mask=attention_mask)
+    
+    def blend_prompt_and_memory_tokens(self, query: str):
+        """
+        Takes care of blending the prompt with the memory tokens:
+        Also returns, if a label is provided, the position of the first token index of the label (for loss comp later on)
+        (Used for the HUB version)
+        """        
+        mem_tokens_str = ''.join(self.decoder_tokenizer.mem_tokens) + self.decoder_tokenizer.sep_token
+        
+        # proper names for "eval" call, don't remove these lines
+        docs = mem_tokens_str * self.generation_top_k
+        question = query
+        
+        prompt_system = 'You are a helpful assistant. Your task is to extract relevant information from provided documents and to answer to questions as briefly as possible.'
+        prompt_user = f"Background:\n{docs}\n\nQuestion:{question}"
+        
+        # Prepare the messages with system and user roles
+        messages = [
+            {"role": "system", "content": prompt_system},
+            {"role": "user", "content": prompt_user.replace(':\ ', ': ')}
+        ]
+
+        # Attempt to apply the system role and catch if it's not supported
+        try:
+            prompt = self.decoder_tokenizer.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)
+            
+        except TemplateError as e:
+            # Catch the error related to system role and handle it (e.g. gemma)
+            if "System role not supported" in str(e):
+                # Remove system role and proceed with only the user role
+                messages = [{"role": "user", "content": messages[0]['content'] + '\n' + messages[1]['content']}]
+                # Apply template again without system role
+                prompt = self.decoder_tokenizer.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)
+            else:
+                # Re-raise the exception if it's unrelated to system role
+                raise e
+
+        return prompt
+
+
+if __name__ == '__main__':
+    cfg = COCOMConfig(decoder_model_name='mistralai/Mistral-7B-Instruct-v0.2',
+                compr_model_name = "mistral_trimmed",
+                compr_rate = 64,
+                compr_n_layers = 5,
+                compr_mlp_hidden_dim = 8096,
+                compr_use_mlp = False, 
+                lora = True, # lora on decoder (and decoder as compr)
+                lora_compressor = True, # lora only on the compressor if it exists
+                training_form = "both",
+                load_adapters = True,
+                kbtc_training = False,
+                optimize_mem_tokens = True,
+                different_mem_tokens = True,
+                attn_implementation = 'flash_attention_2')
+    
+    cocom = COCOM(cfg)
+    
+    cocom.save_pretrained('test_ckpt')
+    
+    del cocom
+    torch.cuda.empty_cache()
+    import gc
+    gc.collect()
+    
+    cocom = COCOM.from_pretrained('test_ckpt')