1/*
2 * Copyright 2012 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#ifndef SkThreadPool_DEFINED
9#define SkThreadPool_DEFINED
10
11#include "SkCondVar.h"
12#include "SkRunnable.h"
13#include "SkTDArray.h"
14#include "SkTInternalLList.h"
15
16class SkThread;
17
18class SkThreadPool {
19
20public:
21    /**
22     * Create a threadpool with count threads, or one thread per core if kThreadPerCore.
23     */
24    static const int kThreadPerCore = -1;
25    explicit SkThreadPool(int count);
26    ~SkThreadPool();
27
28    /**
29     * Queues up an SkRunnable to run when a thread is available, or immediately if
30     * count is 0.  NULL is a safe no-op.  Does not take ownership.
31     */
32    void add(SkRunnable*);
33
34    /**
35     * Block until all added SkRunnables have completed.  Once called, calling add() is undefined.
36     */
37    void wait();
38
39 private:
40    struct LinkedRunnable {
41        // Unowned pointer.
42        SkRunnable* fRunnable;
43
44    private:
45        SK_DECLARE_INTERNAL_LLIST_INTERFACE(LinkedRunnable);
46    };
47
48    enum State {
49        kRunning_State,  // Normal case.  We've been constructed and no one has called wait().
50        kWaiting_State,  // wait has been called, but there still might be work to do or being done.
51        kHalting_State,  // There's no work to do and no thread is busy.  All threads can shut down.
52    };
53
54    SkTInternalLList<LinkedRunnable> fQueue;
55    SkCondVar                        fReady;
56    SkTDArray<SkThread*>             fThreads;
57    State                            fState;
58    int                              fBusyThreads;
59
60    static void Loop(void*);  // Static because we pass in this.
61};
62
63#endif
64