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https://github.com/facebook/sapling.git
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be0cd8da1e
Summary: This is the plumbing to allow us to skip Metadata prefetching during eden prefetches. These can trigger a bunch of wasted network requests when we are fetching files anyways. (These network requests are wasted since we fetch the file contents and most of them are being throttled on sandcastle anyways.) We won't necessarily want to skip metadata prefetching always, we will still want it for the watchman queries, but for `eden prefetch` will probably want to skip it. This is why we are making it an option in the GlobParams. Reviewed By: chadaustin Differential Revision: D24640754 fbshipit-source-id: 20db62d4c0e59fe17cb6535c86ac8f1e3877879c
114 lines
3.1 KiB
C++
114 lines
3.1 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 <optional>
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#include <folly/Range.h>
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#include "eden/fs/model/Hash.h"
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#include "eden/fs/store/ImportPriority.h"
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namespace facebook {
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namespace eden {
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/**
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* ObjectStore calls methods on this context when fetching objects.
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* It's primarily used to track when and why source control objects are fetched.
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*/
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class ObjectFetchContext {
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public:
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/**
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* Which object type was fetched.
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*
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* Suitable for use as an index into an array of size kObjectTypeEnumMax
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*/
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enum ObjectType : unsigned {
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Blob,
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BlobMetadata,
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Tree,
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kObjectTypeEnumMax,
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};
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/**
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* Which cache satisfied a lookup request.
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*
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* Suitable for use as an index into an array of size kOriginEnumMax.
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*/
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enum Origin : unsigned {
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FromMemoryCache,
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FromDiskCache,
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FromBackingStore,
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kOriginEnumMax,
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};
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/**
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* Which interface caused this object fetch
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*/
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enum Cause : unsigned { Unknown, Channel, Thrift };
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ObjectFetchContext() {}
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virtual ~ObjectFetchContext() = default;
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virtual void didFetch(ObjectType, const Hash&, Origin) {}
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virtual std::optional<pid_t> getClientPid() const {
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return std::nullopt;
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}
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virtual Cause getCause() const {
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return ObjectFetchContext::Cause::Unknown;
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}
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virtual std::optional<folly::StringPiece> getCauseDetail() const {
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return std::nullopt;
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}
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virtual ImportPriority getPriority() const {
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return ImportPriority::kNormal();
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}
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virtual bool prefetchMetadata() const {
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return true;
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}
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/**
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* Support deprioritizing in sub-classes.
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* Note: Normally, each ObjectFetchContext is designed to be used for only one
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* import (with NullObjectFetchContext being the only exception currenly).
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* Therefore, this method should only be called once on each
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* ObjectFetchContext object (when it is related to a process doing too much
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* fetches). However, implementations of this method should write the priority
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* change to log as debug information and watch out for unexpected uses of
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* ObjectFetchContext that cause it to be used for more than one import.
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*/
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virtual void deprioritize(uint64_t) {}
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/**
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* Return a no-op fetch context suitable when no tracking is desired.
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*/
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static ObjectFetchContext& getNullContext();
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/**
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* Return a no-op fetch context which has causeDetail field. This field will
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* be logged which in turn can point out "blind spots" in logging i.e. places
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* where null context should be replaces with a real context.
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* Note that this function allocates and return a pointer to a newly allocated
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* memory. This pointer is intented to be used as static variable i.e. static
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* auto ptr = ObjectFetchContext::getNullContextWithCauseDetail("someval");
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*/
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static ObjectFetchContext* getNullContextWithCauseDetail(
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folly::StringPiece causeDetail);
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private:
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ObjectFetchContext(const ObjectFetchContext&) = delete;
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ObjectFetchContext& operator=(const ObjectFetchContext&) = delete;
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};
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} // namespace eden
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} // namespace facebook
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