Metered concurrency: Difference between revisions

Content added Content deleted

Inline

@@ Line 668: / Line 668: @@
     "os"
     "sync"
-    "sync/atomic"
     "time"
 )
@@ Line 675: / Line 674: @@
 type countSem struct {
-    c    int32
+    int
-    cond *sync.Cond
+    sync.Cond
 }
 func newCount(n int) *countSem {
-    return &countSem{int32(n), sync.NewCond(new(sync.Mutex))}
+    return &countSem{n, sync.Cond{L: &sync.Mutex{}}}
 }
 func (cs *countSem) count() int {
+    cs.L.Lock()
-    return int(atomic.LoadInt32(&cs.c))
+    c := cs.int
+    cs.L.Unlock()
+    return c
 }
 func (cs *countSem) acquire() {
+    cs.L.Lock()
-    if atomic.AddInt32(&cs.c, -1) < 0 {
-        atomic.AddInt32(&cs.c, 1)
+    cs.int--
-        cs.cond.L.Lock()
+    for cs.int < 0 {
-        for atomic.AddInt32(&cs.c, -1) < 0 {
+        cs.Wait()
-            atomic.AddInt32(&cs.c, 1)
-            cs.cond.Wait()
-        }
-        cs.cond.L.Unlock()
     }
+    cs.L.Unlock()
 }
 func (cs *countSem) release() {
-    atomic.AddInt32(&cs.c, 1)
+    cs.L.Lock()
-    cs.cond.Signal()
+    cs.int++
+    cs.L.Unlock()
+    cs.Broadcast()
 }
@@ Line 722: / Line 723: @@
     studied.Done()
 }</lang>
 ===Monitor===
 Monitor-style solution implements counting semaphore as a monitor goroutine encapsulating the count.  It implements semaphore operations with separate Go channels.