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Issue 621153003: Move mojo edk into mojo/edk (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: fix checkdeps Created 6 years, 2 months ago
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1 // Copyright 2013 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "mojo/system/waiter.h"
6
7 #include <limits>
8
9 #include "base/logging.h"
10 #include "base/time/time.h"
11
12 namespace mojo {
13 namespace system {
14
15 Waiter::Waiter()
16 : cv_(&lock_),
17 #ifndef NDEBUG
18 initialized_(false),
19 #endif
20 awoken_(false),
21 awake_result_(MOJO_RESULT_INTERNAL),
22 awake_context_(static_cast<uint32_t>(-1)) {
23 }
24
25 Waiter::~Waiter() {
26 }
27
28 void Waiter::Init() {
29 #ifndef NDEBUG
30 initialized_ = true;
31 #endif
32 awoken_ = false;
33 // NOTE(vtl): If performance ever becomes an issue, we can disable the setting
34 // of |awake_result_| (except the first one in |Awake()|) in Release builds.
35 awake_result_ = MOJO_RESULT_INTERNAL;
36 }
37
38 // TODO(vtl): Fast-path the |deadline == 0| case?
39 MojoResult Waiter::Wait(MojoDeadline deadline, uint32_t* context) {
40 base::AutoLock locker(lock_);
41
42 #ifndef NDEBUG
43 DCHECK(initialized_);
44 // It'll need to be re-initialized after this.
45 initialized_ = false;
46 #endif
47
48 // Fast-path the already-awoken case:
49 if (awoken_) {
50 DCHECK_NE(awake_result_, MOJO_RESULT_INTERNAL);
51 if (context)
52 *context = awake_context_;
53 return awake_result_;
54 }
55
56 // |MojoDeadline| is actually a |uint64_t|, but we need a signed quantity.
57 // Treat any out-of-range deadline as "forever" (which is wrong, but okay
58 // since 2^63 microseconds is ~300000 years). Note that this also takes care
59 // of the |MOJO_DEADLINE_INDEFINITE| (= 2^64 - 1) case.
60 if (deadline > static_cast<uint64_t>(std::numeric_limits<int64_t>::max())) {
61 do {
62 cv_.Wait();
63 } while (!awoken_);
64 } else {
65 // NOTE(vtl): This is very inefficient on POSIX, since pthreads condition
66 // variables take an absolute deadline.
67 const base::TimeTicks end_time =
68 base::TimeTicks::Now() +
69 base::TimeDelta::FromMicroseconds(static_cast<int64_t>(deadline));
70 do {
71 base::TimeTicks now_time = base::TimeTicks::Now();
72 if (now_time >= end_time)
73 return MOJO_RESULT_DEADLINE_EXCEEDED;
74
75 cv_.TimedWait(end_time - now_time);
76 } while (!awoken_);
77 }
78
79 DCHECK_NE(awake_result_, MOJO_RESULT_INTERNAL);
80 if (context)
81 *context = awake_context_;
82 return awake_result_;
83 }
84
85 void Waiter::Awake(MojoResult result, uint32_t context) {
86 base::AutoLock locker(lock_);
87
88 if (awoken_)
89 return;
90
91 awoken_ = true;
92 awake_result_ = result;
93 awake_context_ = context;
94 cv_.Signal();
95 // |cv_.Wait()|/|cv_.TimedWait()| will return after |lock_| is released.
96 }
97
98 } // namespace system
99 } // namespace mojo
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