In-memory cache for modules. More...

#include "clang/Serialization/InMemoryModuleCache.h"

Inheritance diagram for clang::InMemoryModuleCache:

Public Types
enum	State { Unknown , Tentative , ToBuild , Final }
	There are four states for a PCM. More...

Public Member Functions
State	getPCMState (llvm::StringRef Filename) const
	Get the state of the PCM.
llvm::MemoryBuffer &	addPCM (llvm::StringRef Filename, std::unique_ptr< llvm::MemoryBuffer > Buffer, off_t Size, time_t ModTime)
	Store the PCM under the Filename.
llvm::MemoryBuffer &	addBuiltPCM (llvm::StringRef Filename, std::unique_ptr< llvm::MemoryBuffer > Buffer, off_t Size, time_t ModTime)
	Store a just-built PCM under the Filename.
bool	tryToDropPCM (llvm::StringRef Filename)
	Try to remove a buffer from the cache.
void	finalizePCM (llvm::StringRef Filename)
	Mark a PCM as final.
llvm::MemoryBuffer *	lookupPCM (llvm::StringRef Filename, off_t &Size, time_t &ModTime) const
	Get a pointer to the PCM if it exists and set `Size` and `ModTime` to its on-disk size and modification time.
bool	isPCMFinal (llvm::StringRef Filename) const
	Check whether the PCM is final and has been shown to work.
bool	shouldBuildPCM (llvm::StringRef Filename) const
	Check whether the PCM is waiting to be built.

Detailed Description

In-memory cache for modules.

This is a cache for modules for use across a compilation, sharing state between the CompilerInstances in a modules build. It must be shared by each CompilerInstance, ASTReader, ASTWriter, and ModuleManager that are coordinating.

Critically, it ensures that a single process has a consistent view of each implicitly-built PCM. This is used by CompilerInstance when building PCMs to ensure that each ModuleManager sees the same files.

Definition at line 29 of file InMemoryModuleCache.h.

Member Enumeration Documentation

◆ State

enum clang::InMemoryModuleCache::State

There are four states for a PCM.

It must monotonically increase.

Unknown: the PCM has neither been read from disk nor built.
Tentative: the PCM has been read from disk but not yet imported or built. It might work.
ToBuild: the PCM read from disk did not work but a new one has not been built yet.
Final: indicating that the current PCM was either built in this process or has been successfully imported.

Enumerator
Unknown
Tentative
ToBuild
Final

Definition at line 64 of file InMemoryModuleCache.h.

Member Function Documentation

◆ addBuiltPCM()

llvm::MemoryBuffer & InMemoryModuleCache::addBuiltPCM	(	llvm::StringRef	Filename,
		std::unique_ptr< llvm::MemoryBuffer >	Buffer,
		off_t	Size,
		time_t	ModTime )

Store a just-built PCM under the Filename.

Precondition: state is Unknown or ToBuild.; state is not Tentative.

Returns: a reference to the buffer as a convenience.

Definition at line 35 of file InMemoryModuleCache.cpp.

Referenced by clang::serialization::ModuleManager::addModule(), and compileModuleImpl().

◆ addPCM()

llvm::MemoryBuffer & InMemoryModuleCache::addPCM	(	llvm::StringRef	Filename,
		std::unique_ptr< llvm::MemoryBuffer >	Buffer,
		off_t	Size,
		time_t	ModTime )

Store the PCM under the Filename.

Precondition: state is Unknown

Postcondition: state is Tentative

Returns: a reference to the buffer as a convenience.

Definition at line 25 of file InMemoryModuleCache.cpp.

Referenced by clang::serialization::ModuleManager::addModule().

◆ finalizePCM()

void InMemoryModuleCache::finalizePCM ( llvm::StringRef Filename )

Mark a PCM as final.

Precondition: state is Tentative or Final.

Postcondition: state is Final.

Definition at line 81 of file InMemoryModuleCache.cpp.

◆ getPCMState()

InMemoryModuleCache::State InMemoryModuleCache::getPCMState ( llvm::StringRef Filename ) const

Get the state of the PCM.

Definition at line 15 of file InMemoryModuleCache.cpp.

References Final, Tentative, ToBuild, and Unknown.

Referenced by isPCMFinal(), and shouldBuildPCM().

◆ isPCMFinal()

bool InMemoryModuleCache::isPCMFinal ( llvm::StringRef Filename ) const

Check whether the PCM is final and has been shown to work.

Returns: true iff state is Final.

Definition at line 59 of file InMemoryModuleCache.cpp.

References Final, and getPCMState().

◆ lookupPCM()

llvm::MemoryBuffer * InMemoryModuleCache::lookupPCM	(	llvm::StringRef	Filename,
		off_t &	Size,
		time_t &	ModTime ) const

Get a pointer to the PCM if it exists and set Size and ModTime to its on-disk size and modification time.

Otherwise, return nullptr and don't change Size and ModTime.

Definition at line 48 of file InMemoryModuleCache.cpp.

Referenced by clang::ASTReader::readASTFileControlBlock().

◆ shouldBuildPCM()

bool InMemoryModuleCache::shouldBuildPCM ( llvm::StringRef Filename ) const

Check whether the PCM is waiting to be built.

Returns: true iff state is ToBuild.

Definition at line 63 of file InMemoryModuleCache.cpp.

References getPCMState(), and ToBuild.

◆ tryToDropPCM()

bool InMemoryModuleCache::tryToDropPCM ( llvm::StringRef Filename )

Try to remove a buffer from the cache.

No effect if state is Final.

Precondition: state is Tentative/Final.

Postcondition: Tentative => ToBuild or Final => Final.

Returns: false on success, i.e. if Tentative => ToBuild.

Definition at line 67 of file InMemoryModuleCache.cpp.

The documentation for this class was generated from the following files:

include/clang/Serialization/InMemoryModuleCache.h
lib/Serialization/InMemoryModuleCache.cpp

Public Types

Public Member Functions