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-rw-r--r--les/execqueue.go86
-rw-r--r--les/execqueue_test.go62
2 files changed, 118 insertions, 30 deletions
diff --git a/les/execqueue.go b/les/execqueue.go
index ac779003b..614721bf0 100644
--- a/les/execqueue.go
+++ b/les/execqueue.go
@@ -16,56 +16,82 @@
package les
-import (
- "sync/atomic"
-)
+import "sync"
-// ExecQueue implements a queue that executes function calls in a single thread,
+// execQueue implements a queue that executes function calls in a single thread,
// in the same order as they have been queued.
type execQueue struct {
- chn chan func()
- cnt, stop, capacity int32
+ mu sync.Mutex
+ cond *sync.Cond
+ funcs []func()
+ closeWait chan struct{}
}
-// NewExecQueue creates a new execution queue.
-func newExecQueue(capacity int32) *execQueue {
- q := &execQueue{
- chn: make(chan func(), capacity),
- capacity: capacity,
- }
+// newExecQueue creates a new execution queue.
+func newExecQueue(capacity int) *execQueue {
+ q := &execQueue{funcs: make([]func(), 0, capacity)}
+ q.cond = sync.NewCond(&q.mu)
go q.loop()
return q
}
func (q *execQueue) loop() {
- for f := range q.chn {
- atomic.AddInt32(&q.cnt, -1)
- if atomic.LoadInt32(&q.stop) != 0 {
- return
- }
+ for f := q.waitNext(false); f != nil; f = q.waitNext(true) {
f()
}
+ close(q.closeWait)
}
-// CanQueue returns true if more function calls can be added to the execution queue.
+func (q *execQueue) waitNext(drop bool) (f func()) {
+ q.mu.Lock()
+ if drop {
+ // Remove the function that just executed. We do this here instead of when
+ // dequeuing so len(q.funcs) includes the function that is running.
+ q.funcs = append(q.funcs[:0], q.funcs[1:]...)
+ }
+ for !q.isClosed() {
+ if len(q.funcs) > 0 {
+ f = q.funcs[0]
+ break
+ }
+ q.cond.Wait()
+ }
+ q.mu.Unlock()
+ return f
+}
+
+func (q *execQueue) isClosed() bool {
+ return q.closeWait != nil
+}
+
+// canQueue returns true if more function calls can be added to the execution queue.
func (q *execQueue) canQueue() bool {
- return atomic.LoadInt32(&q.stop) == 0 && atomic.LoadInt32(&q.cnt) < q.capacity
+ q.mu.Lock()
+ ok := !q.isClosed() && len(q.funcs) < cap(q.funcs)
+ q.mu.Unlock()
+ return ok
}
-// Queue adds a function call to the execution queue. Returns true if successful.
+// queue adds a function call to the execution queue. Returns true if successful.
func (q *execQueue) queue(f func()) bool {
- if atomic.LoadInt32(&q.stop) != 0 {
- return false
+ q.mu.Lock()
+ ok := !q.isClosed() && len(q.funcs) < cap(q.funcs)
+ if ok {
+ q.funcs = append(q.funcs, f)
+ q.cond.Signal()
}
- if atomic.AddInt32(&q.cnt, 1) > q.capacity {
- atomic.AddInt32(&q.cnt, -1)
- return false
- }
- q.chn <- f
- return true
+ q.mu.Unlock()
+ return ok
}
-// Stop stops the exec queue.
+// quit stops the exec queue.
+// quit waits for the current execution to finish before returning.
func (q *execQueue) quit() {
- atomic.StoreInt32(&q.stop, 1)
+ q.mu.Lock()
+ if !q.isClosed() {
+ q.closeWait = make(chan struct{})
+ q.cond.Signal()
+ }
+ q.mu.Unlock()
+ <-q.closeWait
}
diff --git a/les/execqueue_test.go b/les/execqueue_test.go
new file mode 100644
index 000000000..cd45b03f2
--- /dev/null
+++ b/les/execqueue_test.go
@@ -0,0 +1,62 @@
+// Copyright 2017 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package les
+
+import (
+ "testing"
+)
+
+func TestExecQueue(t *testing.T) {
+ var (
+ N = 10000
+ q = newExecQueue(N)
+ counter int
+ execd = make(chan int)
+ testexit = make(chan struct{})
+ )
+ defer q.quit()
+ defer close(testexit)
+
+ check := func(state string, wantOK bool) {
+ c := counter
+ counter++
+ qf := func() {
+ select {
+ case execd <- c:
+ case <-testexit:
+ }
+ }
+ if q.canQueue() != wantOK {
+ t.Fatalf("canQueue() == %t for %s", !wantOK, state)
+ }
+ if q.queue(qf) != wantOK {
+ t.Fatalf("canQueue() == %t for %s", !wantOK, state)
+ }
+ }
+
+ for i := 0; i < N; i++ {
+ check("queue below cap", true)
+ }
+ check("full queue", false)
+ for i := 0; i < N; i++ {
+ if c := <-execd; c != i {
+ t.Fatal("execution out of order")
+ }
+ }
+ q.quit()
+ check("closed queue", false)
+}