6024e5c395
clang 20.0.0 (based on r547379) from build 12806354. Bug: http://b/379133546 Test: N/A Change-Id: I2eb8938af55d809de674be63cb30cf27e801862b Upstream-Commit: ad834e67b1105d15ef907f6255d4c96e8e733f57
80 lines
3.4 KiB
C++
80 lines
3.4 KiB
C++
//===- Caching.h - LLVM Local File Cache ------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the CachedFileStream and the localCache function, which
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// simplifies caching files on the local filesystem in a directory whose
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// contents are managed by a CachePruningPolicy.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_CACHING_H
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#define LLVM_SUPPORT_CACHING_H
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#include "llvm/Support/Error.h"
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namespace llvm {
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class MemoryBuffer;
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/// This class wraps an output stream for a file. Most clients should just be
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/// able to return an instance of this base class from the stream callback, but
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/// if a client needs to perform some action after the stream is written to,
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/// that can be done by deriving from this class and overriding the destructor.
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class CachedFileStream {
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public:
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CachedFileStream(std::unique_ptr<raw_pwrite_stream> OS,
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std::string OSPath = "")
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: OS(std::move(OS)), ObjectPathName(OSPath) {}
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std::unique_ptr<raw_pwrite_stream> OS;
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std::string ObjectPathName;
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virtual ~CachedFileStream() = default;
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};
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/// This type defines the callback to add a file that is generated on the fly.
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///
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/// Stream callbacks must be thread safe.
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using AddStreamFn = std::function<Expected<std::unique_ptr<CachedFileStream>>(
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unsigned Task, const Twine &ModuleName)>;
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/// This is the type of a file cache. To request an item from the cache, pass a
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/// unique string as the Key. For hits, the cached file will be added to the
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/// link and this function will return AddStreamFn(). For misses, the cache will
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/// return a stream callback which must be called at most once to produce
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/// content for the stream. The file stream produced by the stream callback will
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/// add the file to the link after the stream is written to. ModuleName is the
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/// unique module identifier for the bitcode module the cache is being checked
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/// for.
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///
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/// Clients generally look like this:
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///
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/// if (AddStreamFn AddStream = Cache(Task, Key, ModuleName))
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/// ProduceContent(AddStream);
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using FileCache = std::function<Expected<AddStreamFn>(
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unsigned Task, StringRef Key, const Twine &ModuleName)>;
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/// This type defines the callback to add a pre-existing file (e.g. in a cache).
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///
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/// Buffer callbacks must be thread safe.
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using AddBufferFn = std::function<void(unsigned Task, const Twine &ModuleName,
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std::unique_ptr<MemoryBuffer> MB)>;
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/// Create a local file system cache which uses the given cache name, temporary
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/// file prefix, cache directory and file callback. This function does not
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/// immediately create the cache directory if it does not yet exist; this is
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/// done lazily the first time a file is added. The cache name appears in error
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/// messages for errors during caching. The temporary file prefix is used in the
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/// temporary file naming scheme used when writing files atomically.
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Expected<FileCache> localCache(
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const Twine &CacheNameRef, const Twine &TempFilePrefixRef,
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const Twine &CacheDirectoryPathRef,
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AddBufferFn AddBuffer = [](size_t Task, const Twine &ModuleName,
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std::unique_ptr<MemoryBuffer> MB) {});
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} // namespace llvm
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#endif
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