Improve logging performance and separation (#421)

README.md

@@ -203,23 +203,26 @@ As a safeguard, llama-swap also sets `X-Accel-Buffering: no` on SSE responses. H
 
 ## Monitoring Logs on the CLI
 
-```shell
+```sh
 # sends up to the last 10KB of logs
-curl http://host/logs'
+$ curl http://host/logs
 
 # streams combined logs
-curl -Ns 'http://host/logs/stream'
+curl -Ns http://host/logs/stream
+
+# stream llama-swap's proxy status logs
+curl -Ns http://host/logs/stream/proxy
 
-# just llama-swap's logs
-curl -Ns 'http://host/logs/stream/proxy'
+# stream logs from upstream processes that llama-swap loads
+curl -Ns http://host/logs/stream/upstream
 
-# just upstream's logs
-curl -Ns 'http://host/logs/stream/upstream'
+# stream logs only from a specific model
+curl -Ns http://host/logs/stream/{model_id}
 
 # stream and filter logs with linux pipes
 curl -Ns http://host/logs/stream | grep 'eval time'
 
-# skips history and just streams new log entries
+# appending ?no-history will disable sending buffered history first
 curl -Ns 'http://host/logs/stream?no-history'
 ```
 

ai-plans/2025-12-14-efficient-ring-buffer.md

@@ -0,0 +1,85 @@
+# Replace ring.Ring with Efficient Circular Byte Buffer
+
+## Overview
+
+Replace the inefficient `container/ring.Ring` implementation in `logMonitor.go` with a simple circular byte buffer that uses a single contiguous `[]byte` slice. This eliminates per-write allocations, improves cache locality, and correctly implements a 10KB buffer.
+
+## Current Issues
+
+1. `ring.New(10 * 1024)` creates 10,240 ring **elements**, not 10KB of storage
+2. Every `Write()` call allocates a new `[]byte` slice inside the lock
+3. `GetHistory()` iterates all 10,240 elements and appends repeatedly (geometric reallocs)
+4. Linked list structure has poor cache locality and pointer overhead
+
+## Design Requirements
+
+### New CircularBuffer Type
+
+Create a simple circular byte buffer with:
+- Single pre-allocated `[]byte` of fixed capacity (10KB)
+- `head` and `size` integers to track write position and data length
+- No per-write allocations
+
+### API Requirements
+
+The new buffer must support:
+1. **Write(p []byte)** - Append bytes, overwriting oldest data when full
+2. **GetHistory() []byte** - Return all buffered data in correct order (oldest to newest)
+
+### Implementation Details
+
+```go
+type circularBuffer struct {
+    data []byte  // pre-allocated capacity
+    head int     // next write position
+    size int     // current number of bytes stored (0 to cap)
+}
+```
+
+**Write logic:**
+- If `len(p) >= capacity`: just keep the last `capacity` bytes
+- Otherwise: write bytes at `head`, wrapping around if needed
+- Update `head` and `size` accordingly
+- Data is copied into the internal buffer (not stored by reference)
+
+**GetHistory logic:**
+- Calculate start position: `(head - size + cap) % cap`
+- If not wrapped: single slice copy
+- If wrapped: two copies (end of buffer + beginning)
+- Returns a **new slice** (copy), not a view into internal buffer
+
+### Immutability Guarantees (must preserve)
+
+Per existing tests:
+1. Modifying input `[]byte` after `Write()` must not affect stored data
+2. `GetHistory()` returns independent copy - modifications don't affect buffer
+
+## Files to Modify
+
+- `proxy/logMonitor.go` - Replace `buffer *ring.Ring` with new circular buffer
+
+## Testing Plan
+
+Existing tests in `logMonitor_test.go` should continue to pass:
+- `TestLogMonitor` - Basic write/read and subscriber notification
+- `TestWrite_ImmutableBuffer` - Verify writes don't affect returned history
+- `TestWrite_LogTimeFormat` - Timestamp formatting
+
+Add new tests:
+- Test buffer wrap-around behavior
+- Test large writes that exceed buffer capacity
+- Test exact capacity boundary conditions
+
+## Checklist
+
+- [ ] Create `circularBuffer` struct in `logMonitor.go`
+- [ ] Implement `Write()` method for circular buffer
+- [ ] Implement `GetHistory()` method for circular buffer
+- [ ] Update `LogMonitor` struct to use new buffer
+- [ ] Update `NewLogMonitorWriter()` to initialize new buffer
+- [ ] Update `LogMonitor.Write()` to use new buffer
+- [ ] Update `LogMonitor.GetHistory()` to use new buffer
+- [ ] Remove `"container/ring"` import
+- [ ] Run `make test-dev` to verify existing tests pass
+- [ ] Add wrap-around test case
+- [ ] Run `make test-all` for final validation

proxy/logMonitor.go

@@ -1,7 +1,6 @@
 package proxy
 
 import (
-	"container/ring"
 	"context"
 	"fmt"
 	"io"
@@ -12,19 +11,100 @@ import (
 	"github.com/mostlygeek/llama-swap/event"
 )
 
+// circularBuffer is a fixed-size circular byte buffer that overwrites
+// oldest data when full. It provides O(1) writes and O(n) reads.
+type circularBuffer struct {
+	data []byte // pre-allocated capacity
+	head int    // next write position
+	size int    // current number of bytes stored (0 to cap)
+}
+
+func newCircularBuffer(capacity int) *circularBuffer {
+	return &circularBuffer{
+		data: make([]byte, capacity),
+		head: 0,
+		size: 0,
+	}
+}
+
+// Write appends bytes to the buffer, overwriting oldest data when full.
+// Data is copied into the internal buffer (not stored by reference).
+func (cb *circularBuffer) Write(p []byte) {
+	if len(p) == 0 {
+		return
+	}
+
+	cap := len(cb.data)
+
+	// If input is larger than capacity, only keep the last cap bytes
+	if len(p) >= cap {
+		copy(cb.data, p[len(p)-cap:])
+		cb.head = 0
+		cb.size = cap
+		return
+	}
+
+	// Calculate how much space is available from head to end of buffer
+	firstPart := cap - cb.head
+	if firstPart >= len(p) {
+		// All data fits without wrapping
+		copy(cb.data[cb.head:], p)
+		cb.head = (cb.head + len(p)) % cap
+	} else {
+		// Data wraps around
+		copy(cb.data[cb.head:], p[:firstPart])
+		copy(cb.data[:len(p)-firstPart], p[firstPart:])
+		cb.head = len(p) - firstPart
+	}
+
+	// Update size
+	cb.size += len(p)
+	if cb.size > cap {
+		cb.size = cap
+	}
+}
+
+// GetHistory returns all buffered data in correct order (oldest to newest).
+// Returns a new slice (copy), not a view into internal buffer.
+func (cb *circularBuffer) GetHistory() []byte {
+	if cb.size == 0 {
+		return nil
+	}
+
+	result := make([]byte, cb.size)
+	cap := len(cb.data)
+
+	// Calculate start position (oldest data)
+	start := (cb.head - cb.size + cap) % cap
+
+	if start+cb.size <= cap {
+		// Data is contiguous, single copy
+		copy(result, cb.data[start:start+cb.size])
+	} else {
+		// Data wraps around, two copies
+		firstPart := cap - start
+		copy(result[:firstPart], cb.data[start:])
+		copy(result[firstPart:], cb.data[:cb.size-firstPart])
+	}
+
+	return result
+}
+
 type LogLevel int
 
 const (
 	LevelDebug LogLevel = iota
 	LevelInfo
 	LevelWarn
 	LevelError
+
+	LogBufferSize = 100 * 1024
 )
 
 type LogMonitor struct {
 	eventbus *event.Dispatcher
 	mu       sync.RWMutex
-	buffer   *ring.Ring
+	buffer   *circularBuffer
 	bufferMu sync.RWMutex
 
 	// typically this can be os.Stdout
@@ -45,7 +125,7 @@ func NewLogMonitor() *LogMonitor {
 func NewLogMonitorWriter(stdout io.Writer) *LogMonitor {
 	return &LogMonitor{
 		eventbus:   event.NewDispatcherConfig(1000),
-		buffer:     ring.New(10 * 1024), // keep 10KB of buffered logs
+		buffer:     nil, // lazy initialized on first Write
 		stdout:     stdout,
 		level:      LevelInfo,
 		prefix:     "",
@@ -64,29 +144,34 @@ func (w *LogMonitor) Write(p []byte) (n int, err error) {
 	}
 
 	w.bufferMu.Lock()
-	bufferCopy := make([]byte, len(p))
-	copy(bufferCopy, p)
-	w.buffer.Value = bufferCopy
-	w.buffer = w.buffer.Next()
+	if w.buffer == nil {
+		w.buffer = newCircularBuffer(LogBufferSize)
+	}
+	w.buffer.Write(p)
 	w.bufferMu.Unlock()
 
+	// Make a copy for broadcast to preserve immutability
+	bufferCopy := make([]byte, len(p))
+	copy(bufferCopy, p)
 	w.broadcast(bufferCopy)
 	return n, nil
 }
 
 func (w *LogMonitor) GetHistory() []byte {
 	w.bufferMu.RLock()
 	defer w.bufferMu.RUnlock()
+	if w.buffer == nil {
+		return nil
+	}
+	return w.buffer.GetHistory()
+}
 
-	var history []byte
-	w.buffer.Do(func(p any) {
-		if p != nil {
-			if content, ok := p.([]byte); ok {
-				history = append(history, content...)
-			}
-		}
-	})
-	return history
+// Clear releases the buffer memory, making it eligible for GC.
+// The buffer will be lazily re-allocated on the next Write.
+func (w *LogMonitor) Clear() {
+	w.bufferMu.Lock()
+	w.buffer = nil
+	w.bufferMu.Unlock()
 }
 
 func (w *LogMonitor) OnLogData(callback func(data []byte)) context.CancelFunc {