blob: 0da265456350c045b5e9f42d8ed10bcf2e217883 [file] [log] [blame]
// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <stdint.h>
#include "base/macros.h"
#include "mojo/core/ports/port_ref.h"
namespace mojo {
namespace core {
namespace ports {
class Port;
class PortRef;
// A helper which must be used to acquire individual Port locks. Any given
// thread may have at most one of these alive at any time. This ensures that
// when multiple ports are locked, they're locked in globally consistent order.
// Port locks are acquired upon construction of this object and released upon
// destruction.
class PortLocker {
// Constructs a PortLocker over a sequence of |num_ports| contiguous
// |PortRef*|s. The sequence may be reordered by this constructor, and upon
// return, all referenced ports' locks are held.
PortLocker(const PortRef** port_refs, size_t num_ports);
// Provides safe access to a PortRef's Port. Note that in release builds this
// doesn't do anything other than pass through to the private accessor on
// |port_ref|, but it does force callers to go through a PortLocker to get to
// the state, thus minimizing the likelihood that they'll go and do something
// stupid.
Port* GetPort(const PortRef& port_ref) const {
// Sanity check when DCHECK is on to ensure this is actually a port whose
// lock is held by this PortLocker.
bool is_port_locked = false;
for (size_t i = 0; i < num_ports_ && !is_port_locked; ++i)
if (port_refs_[i]->port() == port_ref.port())
is_port_locked = true;
return port_ref.port();
// A helper which can be used to verify that no Port locks are held on the
// current thread. In non-DCHECK builds this is a no-op.
static void AssertNoPortsLockedOnCurrentThread();
static void AssertNoPortsLockedOnCurrentThread() {}
const PortRef** const port_refs_;
const size_t num_ports_;
// Convenience wrapper for a PortLocker that locks a single port.
class SinglePortLocker {
explicit SinglePortLocker(const PortRef* port_ref);
Port* port() const { return locker_.GetPort(*port_ref_); }
const PortRef* port_ref_;
PortLocker locker_;
} // namespace ports
} // namespace core
} // namespace mojo