mirror of
https://github.com/facebook/sapling.git
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fe0ea26fdf
Summary: Looking at strobelight when performing an `eden prefetch` shows that a lot of time is spent copying data around. The list of hash to prefetch is for instance copied 4 times, let's reduce this to only one time when converting Hash to a ByteRange. Reviewed By: chadaustin Differential Revision: D30433285 fbshipit-source-id: 922e6e5c095bd700ee133e9bb219904baf2ae1ac
127 lines
3.9 KiB
C++
127 lines
3.9 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This software may be used and distributed according to the terms of the
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* GNU General Public License version 2.
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*/
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#pragma once
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#include <folly/Range.h>
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#include <folly/futures/Future.h>
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#include <memory>
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#include "eden/fs/model/RootId.h"
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#include "eden/fs/store/ImportPriority.h"
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#include "eden/fs/store/ObjectFetchContext.h"
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#include "eden/fs/utils/PathFuncs.h"
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namespace folly {
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template <typename T>
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class Future;
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}
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namespace facebook::eden {
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class Blob;
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class Hash;
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class Tree;
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class TreeEntry;
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enum class TreeEntryType : uint8_t;
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/**
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* Abstract interface for a BackingStore.
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*
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* A BackingStore fetches tree and blob information from an external
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* authoritative data source.
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*
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* BackingStore implementations must be thread-safe, and perform their own
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* internal locking.
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*/
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class BackingStore : public RootIdCodec {
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public:
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BackingStore() {}
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virtual ~BackingStore() {}
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virtual folly::SemiFuture<std::unique_ptr<Tree>> getRootTree(
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const RootId& rootId,
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ObjectFetchContext& context) = 0;
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/**
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* The API should accept object id instead of rootId. But Object is currently
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* a fixed 20 bytes, so temporariorly use rootId instead.
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* TODO: Replace rootID with objectId once objectId is widened.
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*/
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virtual folly::SemiFuture<std::unique_ptr<TreeEntry>> getTreeEntryForRootId(
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const RootId& rootId,
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TreeEntryType treeEntryType,
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facebook::eden::PathComponentPiece pathComponentPiece,
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ObjectFetchContext& context) = 0;
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virtual folly::SemiFuture<std::unique_ptr<Tree>> getTree(
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const Hash& id,
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ObjectFetchContext& context) = 0;
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virtual folly::SemiFuture<std::unique_ptr<Blob>> getBlob(
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const Hash& id,
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ObjectFetchContext& context) = 0;
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/**
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* Prefetch all the blobs represented by the HashRange.
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*
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* The caller is responsible for making sure that the HashRange stays valid
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* for as long as the returned SemiFuture.
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*/
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FOLLY_NODISCARD virtual folly::SemiFuture<folly::Unit> prefetchBlobs(
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HashRange /*ids*/,
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ObjectFetchContext& /*context*/) {
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return folly::unit;
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}
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virtual void periodicManagementTask() {}
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/**
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* Subclass of BackingStore will override these functions to record file paths
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* fetched. By default, recordFetch() does nothing. After
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* startRecordingFetch() is called, recordFetch() starts to records fetched
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* file paths. stopRecordingFetch() will disable recordFetch()'s function and
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* return the fetched files since startRecordingFetch() is called and clear
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* the old records.
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*
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* Currently implemented in HgQueuedBackingStore.
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*
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* Note: Only stopRecordingFetch() clears old records. Calling
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* startRecordingFetch() a second time has no effect.
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*/
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virtual void startRecordingFetch() {}
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virtual void recordFetch(folly::StringPiece) {}
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virtual std::unordered_set<std::string> stopRecordingFetch() {
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return {};
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}
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/**
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* Directly import a manifest for a root.
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*
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* Subclasses of BackingStore can override this to opportunistically import
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* known manifests for a particular root.
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*
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* This is called when the hg client informs EdenFS of a root to manifest
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* mapping. This is useful when the commit has just been created, as
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* EdenFS won't be able to find out the manifest from the import helper
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* until it re-opens the repo.
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*
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* TODO: When EdenFS no longer uses hg import helper subprocesses and when
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* Hash is widened to variable-width, eliminating the need for proxy hashes,
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* this API should be removed.
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*/
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virtual folly::SemiFuture<folly::Unit> importManifestForRoot(
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const RootId& /*rootId*/,
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const Hash& /*manifest*/) {
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return folly::unit;
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}
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private:
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// Forbidden copy constructor and assignment operator
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BackingStore(BackingStore const&) = delete;
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BackingStore& operator=(BackingStore const&) = delete;
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};
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} // namespace facebook::eden
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