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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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
#ifndef MOZILLA_GFX_USERDATA_H_
#define MOZILLA_GFX_USERDATA_H_
#include <stdlib.h>
#include "Types.h"
#include "mozilla/Assertions.h"
#include "mozilla/Atomics.h"
#include "mozilla/Mutex.h"
namespace mozilla {
namespace gfx {
struct UserDataKey {
int unused;
};
/* this class is basically a clone of the user data concept from cairo */
class UserData {
public:
typedef void (*DestroyFunc)(void* data);
UserData() : count(0), entries(nullptr) {}
/* Attaches untyped userData associated with key. destroy is called on
* destruction */
void Add(UserDataKey* key, void* userData, DestroyFunc destroy) {
for (int i = 0; i < count; i++) {
if (key == entries[i].key) {
if (entries[i].destroy) {
entries[i].destroy(entries[i].userData);
}
entries[i].userData = userData;
entries[i].destroy = destroy;
return;
}
}
// We could keep entries in a std::vector instead of managing it by hand
// but that would propagate an stl dependency out which we'd rather not
// so doing a realloc everytime we add a new entry shouldn't be too costly
entries =
static_cast<Entry*>(realloc(entries, sizeof(Entry) * (count + 1)));
if (!entries) {
MOZ_CRASH("GFX: UserData::Add");
}
entries[count].key = key;
entries[count].userData = userData;
entries[count].destroy = destroy;
count++;
}
/* Remove and return user data associated with key, without destroying it */
void* Remove(UserDataKey* key) {
for (int i = 0; i < count; i++) {
if (key == entries[i].key) {
void* userData = entries[i].userData;
// decrement before looping so entries[i+1] doesn't read past the end:
--count;
for (; i < count; i++) {
entries[i] = entries[i + 1];
}
return userData;
}
}
return nullptr;
}
/* Remove and destroy a given key */
void RemoveAndDestroy(UserDataKey* key) {
for (int i = 0; i < count; i++) {
if (key == entries[i].key) {
if (entries[i].destroy) {
entries[i].destroy(entries[i].userData);
}
// decrement before looping so entries[i+1] doesn't read past the end:
--count;
for (; i < count; i++) {
entries[i] = entries[i + 1];
}
}
}
}
/* Retrives the userData for the associated key */
void* Get(UserDataKey* key) const {
for (int i = 0; i < count; i++) {
if (key == entries[i].key) {
return entries[i].userData;
}
}
return nullptr;
}
bool Has(UserDataKey* key) {
for (int i = 0; i < count; i++) {
if (key == entries[i].key) {
return true;
}
}
return false;
}
void Destroy() {
if (!entries) {
return;
}
for (int i = 0; i < count; i++) {
if (entries[i].destroy) {
entries[i].destroy(entries[i].userData);
}
}
free(entries);
entries = nullptr;
count = 0;
}
~UserData() { Destroy(); }
private:
struct Entry {
const UserDataKey* key;
void* userData;
DestroyFunc destroy;
};
int count;
Entry* entries;
};
class ThreadSafeUserData {
protected:
struct LockedUserData : public UserData {
Mutex mLock;
LockedUserData() : mLock("LockedUserData::mLock") {}
};
public:
~ThreadSafeUserData() {
if (LockedUserData* userData = mUserData.exchange(nullptr)) {
{
MutexAutoLock lock(userData->mLock);
userData->Destroy();
}
delete userData;
}
}
void Add(UserDataKey* key, void* value, UserData::DestroyFunc destroy) {
LockedUserData* userData = GetUserData();
MutexAutoLock lock(userData->mLock);
userData->Add(key, value, destroy);
}
void* Remove(UserDataKey* key) {
LockedUserData* userData = GetUserData();
MutexAutoLock lock(userData->mLock);
return userData->Remove(key);
}
void RemoveAndDestroy(UserDataKey* key) {
LockedUserData* userData = GetUserData();
MutexAutoLock lock(userData->mLock);
userData->RemoveAndDestroy(key);
}
void* Get(UserDataKey* key) const {
LockedUserData* userData = GetUserData();
MutexAutoLock lock(userData->mLock);
return userData->Get(key);
}
bool Has(UserDataKey* key) {
LockedUserData* userData = GetUserData();
MutexAutoLock lock(userData->mLock);
return userData->Has(key);
}
private:
LockedUserData* GetUserData() const {
LockedUserData* userData = mUserData;
if (!userData) {
userData = new LockedUserData;
if (!mUserData.compareExchange(nullptr, userData)) {
delete userData;
userData = mUserData;
MOZ_ASSERT(userData);
}
}
return userData;
}
// The Mutex class is quite large. For small, frequent classes (ScaledFont,
// SourceSurface, etc.) this can add a lot of memory overhead, especially if
// UserData is only infrequently used. To avoid this, we only allocate the
// LockedUserData if it is actually used. If unused, it only adds a single
// pointer as overhead.
mutable Atomic<LockedUserData*> mUserData;
};
} // namespace gfx
} // namespace mozilla
#endif /* MOZILLA_GFX_USERDATA_H_ */