shared_memory_arbiter_impl.h | Explore in Territory

/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * 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 SRC_TRACING_CORE_SHARED_MEMORY_ARBITER_IMPL_H_
#define SRC_TRACING_CORE_SHARED_MEMORY_ARBITER_IMPL_H_

#include <stdint.h>

#include <functional>
#include <map>
#include <memory>
#include <mutex>
#include <vector>

#include "perfetto/ext/base/weak_ptr.h"
#include "perfetto/ext/tracing/core/basic_types.h"
#include "perfetto/ext/tracing/core/shared_memory_abi.h"
#include "perfetto/ext/tracing/core/shared_memory_arbiter.h"
#include "perfetto/tracing/core/forward_decls.h"
#include "src/tracing/core/id_allocator.h"

namespace perfetto {

class PatchList;
class Patch;
class TraceWriter;
class TraceWriterImpl;

namespace base {
class TaskRunner;
}  // namespace base

// This class handles the shared memory buffer on the producer side. It is used
// to obtain thread-local chunks and to partition pages from several threads.
// There is one arbiter instance per Producer.
// This class is thread-safe and uses locks to do so. Data sources are supposed
// to interact with this sporadically, only when they run out of space on their
// current thread-local chunk.
//
// The arbiter can become "unbound" as a consequence of:
//  (a) being created without an endpoint
//  (b) CreateStartupTraceWriter calls after creation (whether created with or
//      without endpoint).
//
// Entering the unbound state is only supported if all trace writers are created
// in kDrop mode. In the unbound state, the arbiter buffers commit messages
// until all trace writers are bound to a target buffer.
//
// The following state transitions are possible:
//
//   CreateInstance()
//    |
//    |  CreateUnboundInstance()
//    |    |
//    |    |
//    |    V
//    |  [ !fully_bound_, !endpoint_, 0 unbound buffer reservations ]
//    |      |     |
//    |      |     | CreateStartupTraceWriter(buf)
//    |      |     |  buffer reservations += buf
//    |      |     |
//    |      |     |             ----
//    |      |     |            |    | CreateStartupTraceWriter(buf)
//    |      |     |            |    |  buffer reservations += buf
//    |      |     V            |    V
//    |      |   [ !fully_bound_, !endpoint_, >=1 unbound buffer reservations ]
//    |      |                                                |
//    |      |                       BindToProducerEndpoint() |
//    |      |                                                |
//    |      | BindToProducerEndpoint()                       |
//    |      |                                                V
//    |      |   [ !fully_bound_, endpoint_, >=1 unbound buffer reservations ]
//    |      |   A    |    A                               |     A
//    |      |   |    |    |                               |     |
//    |      |   |     ----                                |     |
//    |      |   |    CreateStartupTraceWriter(buf)        |     |
//    |      |   |     buffer reservations += buf          |     |
//    |      |   |                                         |     |
//    |      |   | CreateStartupTraceWriter(buf)           |     |
//    |      |   |  where buf is not yet bound             |     |
//    |      |   |  buffer reservations += buf             |     | (yes)
//    |      |   |                                         |     |
//    |      |   |        BindStartupTargetBuffer(buf, id) |-----
//    |      |   |           buffer reservations -= buf    | reservations > 0?
//    |      |   |                                         |
//    |      |   |                                         | (no)
//    |      V   |                                         V
//     --> [ fully_bound_, endpoint_, 0 unbound buffer reservations ]
//              |    A
//              |    | CreateStartupTraceWriter(buf)
//              |    |  where buf is already bound
//               ----
class SharedMemoryArbiterImpl : public SharedMemoryArbiter { … };

}  // namespace perfetto

#endif  // SRC_TRACING_CORE_SHARED_MEMORY_ARBITER_IMPL_H_
chromium/third_party/perfetto/src/tracing/core/shared_memory_arbiter_impl.h
