internal/api.go
func (c *context) flushLog(force bool) (flushed bool) {
	c.pendingLogs.Lock()
	// Grab up to 30 MB. We can get away with up to 32 MB, but let's be cautious.
	n, rem := 0, 30<<20
	for ; n < len(c.pendingLogs.lines); n++ {
		ll := c.pendingLogs.lines[n]
		// Each log line will require about 3 bytes of overhead.
		nb := proto.Size(ll) + 3
		if nb > rem {
			break
		}
		rem -= nb
	}
	lines := c.pendingLogs.lines[:n]
	c.pendingLogs.lines = c.pendingLogs.lines[n:]
	c.pendingLogs.Unlock()

	if len(lines) == 0 && !force {
		// Nothing to flush.
		return false
	}

	rescueLogs := false
	defer func() {
		if rescueLogs {
			c.pendingLogs.Lock()
			c.pendingLogs.lines = append(lines, c.pendingLogs.lines...)
			c.pendingLogs.Unlock()
		}
	}()

	buf, err := proto.Marshal(&logpb.UserAppLogGroup{
		LogLine: lines,
	})
	if err != nil {
		log.Printf("internal.flushLog: marshaling UserAppLogGroup: %v", err)
		rescueLogs = true
		return false
	}

	req := &logpb.FlushRequest{
		Logs: buf,
	}
	res := &basepb.VoidProto{}
	c.pendingLogs.Lock()
	c.pendingLogs.flushes++
	c.pendingLogs.Unlock()
	if err := Call(toContext(c), "logservice", "Flush", req, res); err != nil {
		log.Printf("internal.flushLog: Flush RPC: %v", err)
		rescueLogs = true
		return false
	}
	return true
}
func (c *context) flushLog(force bool) (flushed bool) {
	c.pendingLogs.Lock()
	// Grab up to 30 MB. We can get away with up to 32 MB, but let's be cautious.
	n, rem := 0, 30<<20
	for ; n < len(c.pendingLogs.lines); n++ {
		ll := c.pendingLogs.lines[n]
		// Each log line will require about 3 bytes of overhead.
		nb := proto.Size(ll) + 3
		if nb > rem {
			break
		}
		rem -= nb
	}
	lines := c.pendingLogs.lines[:n]
	c.pendingLogs.lines = c.pendingLogs.lines[n:]
	c.pendingLogs.Unlock()

	if len(lines) == 0 && !force {
		// Nothing to flush.
		return false
	}

	rescueLogs := false
	defer func() {
		if rescueLogs {
			c.pendingLogs.Lock()
			c.pendingLogs.lines = append(lines, c.pendingLogs.lines...)
			c.pendingLogs.Unlock()
		}
	}()

	buf, err := proto.Marshal(&logpb.UserAppLogGroup{
		LogLine: lines,
	})
	if err != nil {
		log.Printf("internal.flushLog: marshaling UserAppLogGroup: %v", err)
		rescueLogs = true
		return false
	}

	req := &logpb.FlushRequest{
		Logs: buf,
	}
	res := &basepb.VoidProto{}
	c.pendingLogs.Lock()
	c.pendingLogs.flushes++
	c.pendingLogs.Unlock()
	if err := Call(toContext(c), "logservice", "Flush", req, res); err != nil {
		log.Printf("internal.flushLog: Flush RPC: %v", err)
		rescueLogs = true
		return false
	}
	return true
}
// flushLog attempts to flush any pending logs to the appserver.
// It should not be called concurrently.