1 // Copyright 2017 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/core/ports/port_locker.h"
6
7 #include <algorithm>
8
9 #include "mojo/core/ports/port.h"
10
11 #if DCHECK_IS_ON()
12 #include "base/threading/thread_local.h"
13 #endif
14
15 namespace mojo {
16 namespace core {
17 namespace ports {
18
19 namespace {
20
21 #if DCHECK_IS_ON()
UpdateTLS(PortLocker * old_locker,PortLocker * new_locker)22 void UpdateTLS(PortLocker* old_locker, PortLocker* new_locker) {
23 // Sanity check when DCHECK is on to make sure there is only ever one
24 // PortLocker extant on the current thread.
25 static auto* tls = new base::ThreadLocalPointer<PortLocker>();
26 DCHECK_EQ(old_locker, tls->Get());
27 tls->Set(new_locker);
28 }
29 #endif
30
31 } // namespace
32
PortLocker(const PortRef ** port_refs,size_t num_ports)33 PortLocker::PortLocker(const PortRef** port_refs, size_t num_ports)
34 : port_refs_(port_refs), num_ports_(num_ports) {
35 #if DCHECK_IS_ON()
36 UpdateTLS(nullptr, this);
37 #endif
38
39 // Sort the ports by address to lock them in a globally consistent order.
40 std::sort(
41 port_refs_, port_refs_ + num_ports_,
42 [](const PortRef* a, const PortRef* b) { return a->port() < b->port(); });
43 for (size_t i = 0; i < num_ports_; ++i) {
44 // TODO(crbug.com/725605): Remove this CHECK.
45 CHECK(port_refs_[i]->port());
46 port_refs_[i]->port()->lock_.Acquire();
47 }
48 }
49
~PortLocker()50 PortLocker::~PortLocker() {
51 for (size_t i = 0; i < num_ports_; ++i)
52 port_refs_[i]->port()->lock_.Release();
53
54 #if DCHECK_IS_ON()
55 UpdateTLS(this, nullptr);
56 #endif
57 }
58
59 #if DCHECK_IS_ON()
60 // static
AssertNoPortsLockedOnCurrentThread()61 void PortLocker::AssertNoPortsLockedOnCurrentThread() {
62 // Forces a DCHECK if the TLS PortLocker is anything other than null.
63 UpdateTLS(nullptr, nullptr);
64 }
65 #endif
66
SinglePortLocker(const PortRef * port_ref)67 SinglePortLocker::SinglePortLocker(const PortRef* port_ref)
68 : port_ref_(port_ref), locker_(&port_ref_, 1) {}
69
70 SinglePortLocker::~SinglePortLocker() = default;
71
72 } // namespace ports
73 } // namespace core
74 } // namespace mojo
75