gecko-dev/dom/media/gtest/TestDataMutex.cpp
Chris Pearce 8eff3a166e Bug 1426291 - Add Rust style mutex template which wraps data with the mutex that synchronizes it. r=jwwang
Rust's std::sync::Mutex has some nice properties. Its philosphy is to lock
data, rather than code.

It wraps data you're trying to make thread safe with a mutex, and in order to
get a reference to the wrapped data you need to lock the mutex and access it
through an intermediate layer. This is good, as the mutex that's protecting
access to the data is explicitly associated with the data, and it's impossible
to forget to take the lock before accessing the data.

This patch adds a similar mutex wrapper to Media Playback code. If it works
well, we can look at moving it into xpcom.

MozReview-Commit-ID: 4APAic6Fh8m

--HG--
extra : rebase_source : 3dc2b4916d3fd31f622af2b0c26ac3c0707d3300
2017-12-20 16:15:09 +13:00

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "gtest/gtest.h"
#include "mozilla/DataMutex.h"
#include "nsTArray.h"
using mozilla::DataMutex;
struct A
{
void Set(int a) { mValue = a; }
int mValue;
};
TEST(DataMutex, Basic)
{
{
DataMutex<uint32_t> i(1, "1");
auto x = i.Lock();
*x = 4;
ASSERT_EQ(*x, 4u);
}
{
DataMutex<A> a({ 4 }, "StructA");
auto x = a.Lock();
ASSERT_EQ(x->mValue, 4);
x->Set(8);
ASSERT_EQ(x->mValue, 8);
}
{
DataMutex<nsTArray<uint32_t>> _a("array");
auto a = _a.Lock();
auto& x = a.ref();
ASSERT_EQ(x.Length(), 0u);
x.AppendElement(1u);
ASSERT_EQ(x.Length(), 1u);
ASSERT_EQ(x[0], 1u);
}
}