100 строки
3.2 KiB
C++
100 строки
3.2 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#pragma once
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#include <better/optional.h>
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#include <chrono>
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#include <react/mounting/MountingTransaction.h>
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#include <react/mounting/ShadowTreeRevision.h>
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#ifdef RN_SHADOW_TREE_INTROSPECTION
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#include <react/mounting/stubs.h>
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#endif
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namespace facebook {
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namespace react {
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/*
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* Stores inside all non-mounted yet revisions of a shadow tree and coordinates
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* mounting. The object stores the most recent mounted revision and the most
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* recent committed one. Then when a new mounting transaction is requested the
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* object generates mutation instructions and returns it as a
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* `MountingTransaction`.
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*/
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class MountingCoordinator final {
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public:
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using Shared = std::shared_ptr<MountingCoordinator const>;
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/*
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* The constructor is ment to be used only inside `ShadowTree`, and it's
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* `public` only to enable using with `std::make_shared<>`.
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*/
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MountingCoordinator(ShadowTreeRevision baseRevision);
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/*
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* Returns the id of the surface that the coordinator belongs to.
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*/
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SurfaceId getSurfaceId() const;
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/*
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* Computes a consequent mounting transaction and returns it.
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* The returning transaction can accumulate multiple recent revisions of a
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* shadow tree. Returns empty optional if there no new shadow tree revision to
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* mount.
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* The method is thread-safe and can be called from any thread.
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* However, a consumer should always call it on the same thread (e.g. on the
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* main thread) or ensure sequentiality of mount transactions separately.
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*/
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better::optional<MountingTransaction> pullTransaction() const;
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/*
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* Blocks the current thread until a new mounting transaction is available or
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* after the specified `timeout` duration.
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* Returns `false` if a timeout occurred before a new transaction available.
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* Call `pullTransaction` right after the method to retrieve the transaction.
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* Similarly to `pullTransaction` this method is thread-safe but the consumer
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* should call it on the same thread (e.g. on the main thread) or ensure
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* sequentiality of mount transactions separately.
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*/
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bool waitForTransaction(std::chrono::duration<double> timeout) const;
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private:
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friend class ShadowTree;
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/*
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* Methods from this section are meant to be used by `ShadowTree` only.
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*/
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void push(ShadowTreeRevision &&revision) const;
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/*
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* Revokes the last pushed `ShadowTreeRevision`.
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* Generating a `MountingTransaction` requires some resources which the
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* `MountingCoordinator` does not own (e.g. `ComponentDescriptor`s). Revoking
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* committed revisions allows the owner (a Shadow Tree) to make sure that
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* those resources will not be accessed (e.g. by the Mouting Layer).
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*/
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void revoke() const;
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private:
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SurfaceId const surfaceId_;
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mutable std::mutex mutex_;
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mutable ShadowTreeRevision baseRevision_;
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mutable better::optional<ShadowTreeRevision> lastRevision_{};
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mutable MountingTransaction::Number number_{0};
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mutable std::condition_variable signal_;
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#ifdef RN_SHADOW_TREE_INTROSPECTION
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mutable StubViewTree stubViewTree_; // Protected by `mutex_`.
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#endif
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};
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} // namespace react
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} // namespace facebook
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