zircon/system/dev/sysmem/sysmem/buffer_collection_token.h

// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef ZIRCON_SYSTEM_DEV_SYSMEM_SYSMEM_BUFFER_COLLECTION_TOKEN_H_
#define ZIRCON_SYSTEM_DEV_SYSMEM_SYSMEM_BUFFER_COLLECTION_TOKEN_H_

#include "logging.h"
#include "logical_buffer_collection.h"

#include <fuchsia/sysmem/c/fidl.h>
#include <lib/fidl-async-2/fidl_server.h>
#include <lib/fidl-async-2/simple_binding.h>

class BufferCollectionToken
    : public FidlServer<
          BufferCollectionToken,
          SimpleBinding<BufferCollectionToken,
                        fuchsia_sysmem_BufferCollectionToken_ops_t,
                        fuchsia_sysmem_BufferCollectionToken_dispatch>,
          vLog> {
public:
    ~BufferCollectionToken();

    zx_status_t Duplicate(uint32_t rights_attenuation_mask,
                          zx_handle_t buffer_collection_token_request);
    zx_status_t Sync(fidl_txn_t* txn);
    zx_status_t Close();

    LogicalBufferCollection* parent();
    fbl::RefPtr<LogicalBufferCollection> parent_shared();

    void SetServerKoid(zx_koid_t server_koid);

    zx_koid_t server_koid();

    bool is_done();

    void SetBufferCollectionRequest(zx::channel buffer_collection_request);

    zx::channel TakeBufferCollectionRequest();

private:
    friend class FidlServer;
    BufferCollectionToken(Device* parent_device,
                          fbl::RefPtr<LogicalBufferCollection> parent,
                          uint32_t rights_attenuation_mask);

    static const fuchsia_sysmem_BufferCollectionToken_ops_t kOps;

    Device* parent_device_ = nullptr;
    fbl::RefPtr<LogicalBufferCollection> parent_;
    // 1 bit means the right is allowed.  0 bit means the right is attenuated.
    uint32_t rights_attenuation_mask_ = 0;

    zx_koid_t server_koid_ = ZX_KOID_INVALID;

    // Becomes true on the first Close() or BindSharedCollection().  This being
    // true means a channel close is not fatal to the LogicalBufferCollection.
    // However, if the client sends a redundant Close(), that is fatal to the
    // BufferCollectionToken and fatal to the LogicalBufferCollection.
    bool is_done_ = false;

    // This is set up to once during
    // LogicalBufferCollection::BindSharedCollection(), and essentially curries
    // the buffer_collection_request past the processing of any remaining
    // inbound messages on the BufferCollectionToken before starting to serve
    // the BufferCollection that the token was exchanged for.  This way, inbound
    // Duplicate() messages in the BufferCollectionToken are seen before any
    // BufferCollection::SetConstraints() (which might otherwise try to allocate
    // buffers too soon before all tokens are gone).
    zx::channel buffer_collection_request_;
};
#endif // ZIRCON_SYSTEM_DEV_SYSMEM_SYSMEM_BUFFER_COLLECTION_TOKEN_H_