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// Copyright 2016 The SwiftShader Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef sw_Resource_hpp
#define sw_Resource_hpp
#include "MutexLock.hpp"
namespace sw
{
enum Accessor
{
PUBLIC, // Application/API access
PRIVATE, // Renderer access, shared by multiple threads if read-only
MANAGED, // Renderer access, shared read/write access if partitioned
EXCLUSIVE
};
// Resource is a form of shared mutex that guards an internally allocated
// buffer. Resource has an exclusive lock mode (sw::Accessor) and lock
// count, defaulting to sw::Accessor::PUBLIC and 0, respectively.
// Resource doesn't treat any of the sw::Accessor enumerator lock modes
// differently, all semantic meaning comes from the usage of Resource.
// You can have multiple locks in mode sw::Accessor::EXCLUSIVE.
class Resource
{
public:
Resource(size_t bytes);
// destruct() is an asynchronous destructor, that will atomically:
// When the resource is unlocked:
// * Delete itself.
// When the resource is locked:
// * Flag itself for deletion when next fully unlocked.
void destruct();
// lock() will atomically:
// When the resource is unlocked OR the lock mode equals claimer:
// * Increment the lock count.
// * Return a pointer to the buffer.
// When the resource is locked AND the lock mode does not equal claimer:
// * Block until all existing locks are released (lock count equals 0).
// * Switch lock mode to claimer.
// * Increment the lock count.
// * Return a pointer to the buffer.
void *lock(Accessor claimer);
// lock() will atomically:
// When the resource is unlocked OR the lock mode equals claimer:
// * Increment the lock count.
// * Return a pointer to the buffer.
// When the resource is locked AND the lock mode equals relinquisher:
// * Release *all* existing locks (regardless of prior count).
// * Delete itself and return nullptr if Resource::destruct() had been called while locked.
// * Switch lock mode to claimer.
// * Increment the lock count to 1.
// * Return a pointer to the buffer.
// When the resource is locked AND the lock mode does not equal relinquisher:
// * Block until all existing locks are released (lock count equals 0)
// * Switch lock mode to claimer
// * Increment the lock count to 1.
// * Return a pointer to the buffer.
void *lock(Accessor relinquisher, Accessor claimer);
// unlock() will atomically:
// * Assert if there are no locks.
// * Release a single lock.
// * Delete itself if Resource::destruct() had been called while locked.
void unlock();
// unlock() will atomically:
// When the resource is locked AND the lock mode equals relinquisher:
// * Release *all* existing locks (regardless of prior count).
// * Delete itself if Resource::destruct() had been called while locked.
// When the resource is not locked OR the lock mode does not equal relinquisher:
// * Do nothing.
void unlock(Accessor relinquisher);
// data() will return the Resource's buffer pointer regardless of lock
// state.
const void *data() const;
// size is the size in bytes of the Resource's buffer.
const size_t size;
private:
~Resource(); // Always call destruct() instead
MutexLock criticalSection;
Event unblock;
volatile int blocked;
volatile Accessor accessor;
volatile int count;
bool orphaned;
void *buffer;
};
}
#endif // sw_Resource_hpp