From 9d45dd9fa4883e23b5cd0933ec5daab9c64a01e7 Mon Sep 17 00:00:00 2001
From: vlastahajek <vlastimil.hajek@bonitoo.io>
Date: Fri, 9 Sep 2022 12:54:39 +0200
Subject: [PATCH] fix: use mutex only if necessary (#352)

---
 CHANGELOG.md                  |  3 +++
 api/write.go                  | 23 +++++++++--------
 api/writeAPIBlocking.go       | 48 +++++++++++++++++++++--------------
 internal/test/http_service.go |  2 ++
 4 files changed, 46 insertions(+), 30 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0ee03ab8..3394a48e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,7 @@
 ## [unreleased]
+### Bug fixes
+- [#354](https://github.com/influxdata/influxdb-client-go/pull/354) More efficient synchronization in WriteAPIBlocking. 
+
 
 ## 2.10.0 [2022-08-25]
 ### Features
diff --git a/api/write.go b/api/write.go
index b6d60ceb..313d21a1 100644
--- a/api/write.go
+++ b/api/write.go
@@ -51,17 +51,18 @@ type WriteAPIImpl struct {
 	service     *iwrite.Service
 	writeBuffer []string
 
-	errCh         chan error
-	writeCh       chan *iwrite.Batch
-	bufferCh      chan string
-	writeStop     chan struct{}
-	bufferStop    chan struct{}
-	bufferFlush   chan struct{}
-	doneCh        chan struct{}
-	bufferInfoCh  chan writeBuffInfoReq
-	writeInfoCh   chan writeBuffInfoReq
-	writeOptions  *write.Options
-	closingMu     *sync.Mutex
+	errCh        chan error
+	writeCh      chan *iwrite.Batch
+	bufferCh     chan string
+	writeStop    chan struct{}
+	bufferStop   chan struct{}
+	bufferFlush  chan struct{}
+	doneCh       chan struct{}
+	bufferInfoCh chan writeBuffInfoReq
+	writeInfoCh  chan writeBuffInfoReq
+	writeOptions *write.Options
+	closingMu    *sync.Mutex
+	// more appropriate Bool type from sync/atomic cannot be used because it is available since go 1.19
 	isErrChReader int32
 }
 
diff --git a/api/writeAPIBlocking.go b/api/writeAPIBlocking.go
index d348aa8f..116ebc43 100644
--- a/api/writeAPIBlocking.go
+++ b/api/writeAPIBlocking.go
@@ -8,6 +8,7 @@ import (
 	"context"
 	"strings"
 	"sync"
+	"sync/atomic"
 
 	http2 "github.com/influxdata/influxdb-client-go/v2/api/http"
 	"github.com/influxdata/influxdb-client-go/v2/api/write"
@@ -51,9 +52,10 @@ type WriteAPIBlocking interface {
 type writeAPIBlocking struct {
 	service      *iwrite.Service
 	writeOptions *write.Options
-	batching     bool
-	batch        []string
-	mu           sync.Mutex
+	// more appropriate Bool type from sync/atomic cannot be used because it is available since go 1.19
+	batching int32
+	batch    []string
+	mu       sync.Mutex
 }
 
 // NewWriteAPIBlocking creates new instance of blocking write client for writing data to bucket belonging to org
@@ -69,28 +71,26 @@ func NewWriteAPIBlockingWithBatching(org string, bucket string, service http2.Se
 }
 
 func (w *writeAPIBlocking) EnableBatching() {
-	w.mu.Lock()
-	defer w.mu.Unlock()
-	if !w.batching {
-		w.batching = true
+	if atomic.LoadInt32(&w.batching) == 0 {
+		w.mu.Lock()
+		w.batching = 1
 		w.batch = make([]string, 0, w.writeOptions.BatchSize())
+		w.mu.Unlock()
 	}
 }
 
 func (w *writeAPIBlocking) write(ctx context.Context, line string) error {
-	w.mu.Lock()
-	defer w.mu.Unlock()
-	body := line
-	if w.batching {
+	if atomic.LoadInt32(&w.batching) > 0 {
+		w.mu.Lock()
+		defer w.mu.Unlock()
 		w.batch = append(w.batch, line)
 		if len(w.batch) == int(w.writeOptions.BatchSize()) {
-			body = strings.Join(w.batch, "\n")
-			w.batch = w.batch[:0]
+			return w.flush(ctx)
 		} else {
 			return nil
 		}
 	}
-	err := w.service.WriteBatch(ctx, iwrite.NewBatch(body, w.writeOptions.MaxRetryTime()))
+	err := w.service.WriteBatch(ctx, iwrite.NewBatch(line, w.writeOptions.MaxRetryTime()))
 	if err != nil {
 		return err
 	}
@@ -112,13 +112,23 @@ func (w *writeAPIBlocking) WritePoint(ctx context.Context, point ...*write.Point
 	return w.write(ctx, line)
 }
 
-func (w *writeAPIBlocking) Flush(ctx context.Context) error {
-	w.mu.Lock()
-	defer w.mu.Unlock()
-	if w.batching && len(w.batch) > 0 {
+// flush is unsychronized helper for creating and sending batch
+// Must be called from synchronized block
+func (w *writeAPIBlocking) flush(ctx context.Context) error {
+	if len(w.batch) > 0 {
 		body := strings.Join(w.batch, "\n")
 		w.batch = w.batch[:0]
-		return w.service.WriteBatch(ctx, iwrite.NewBatch(body, w.writeOptions.MaxRetryTime()))
+		b := iwrite.NewBatch(body, w.writeOptions.MaxRetryTime())
+		return w.service.WriteBatch(ctx, b)
+	}
+	return nil
+}
+
+func (w *writeAPIBlocking) Flush(ctx context.Context) error {
+	if atomic.LoadInt32(&w.batching) > 0 {
+		w.mu.Lock()
+		defer w.mu.Unlock()
+		return w.flush(ctx)
 	}
 	return nil
 }
diff --git a/internal/test/http_service.go b/internal/test/http_service.go
index ff72e3a0..6f35f686 100644
--- a/internal/test/http_service.go
+++ b/internal/test/http_service.go
@@ -123,7 +123,9 @@ func (t *HTTPService) DoHTTPRequestWithResponse(_ *http.Request, _ http2.Request
 // DoPostRequest reads http request, validates URL and stores data in the request
 func (t *HTTPService) DoPostRequest(_ context.Context, url string, body io.Reader, requestCallback http2.RequestCallback, _ http2.ResponseCallback) *http2.Error {
 	req, err := http.NewRequest("POST", url, nil)
+	t.lock.Lock()
 	t.requests++
+	t.lock.Unlock()
 	if err != nil {
 		return http2.NewError(err)
 	}