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[Support/MemoryBuffer] Introduce a boolean parameter (false by default) 'IsVolatile' for the open file functions.

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This provides a hint that the file may be changing often so mmap is avoided.

llvm-svn: 208007
This commit is contained in:
Argyrios Kyrtzidis 2014-05-05 21:55:51 +00:00
parent e5222b0f5a
commit 81db8ad5a3
2 changed files with 50 additions and 24 deletions
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24
include/llvm/Support/MemoryBuffer.h
View File

@ -67,34 +67,46 @@ public:
/// MemoryBuffer if successful, otherwise returning null. If FileSize is
/// specified, this means that the client knows that the file exists and that
/// it has the specified size.
///
/// \param IsVolatile true indicates that the file may be changing often.
static error_code getFile(Twine Filename, OwningPtr<MemoryBuffer> &Result,
int64_t FileSize = -1,
bool RequiresNullTerminator = true);
bool RequiresNullTerminator = true,
bool IsVolatile = false);
static error_code getFile(Twine Filename,
std::unique_ptr<MemoryBuffer> &Result,
int64_t FileSize = -1,
bool RequiresNullTerminator = true);
bool RequiresNullTerminator = true,
bool IsVolatile = false);
/// Given an already-open file descriptor, map some slice of it into a
/// MemoryBuffer. The slice is specified by an \p Offset and \p MapSize.
/// Since this is in the middle of a file, the buffer is not null terminated.
///
/// \param IsVolatile true indicates that the file may be changing often.
static error_code getOpenFileSlice(int FD, const char *Filename,
OwningPtr<MemoryBuffer> &Result,
uint64_t MapSize, int64_t Offset);
uint64_t MapSize, int64_t Offset,
bool IsVolatile = false);
static error_code getOpenFileSlice(int FD, const char *Filename,
std::unique_ptr<MemoryBuffer> &Result,
uint64_t MapSize, int64_t Offset);
uint64_t MapSize, int64_t Offset,
bool IsVolatile = false);
/// Given an already-open file descriptor, read the file and return a
/// MemoryBuffer.
///
/// \param IsVolatile true indicates that the file may be changing often.
static error_code getOpenFile(int FD, const char *Filename,
OwningPtr<MemoryBuffer> &Result,
uint64_t FileSize,
bool RequiresNullTerminator = true);
bool RequiresNullTerminator = true,
bool IsVolatile = false);
static error_code getOpenFile(int FD, const char *Filename,
std::unique_ptr<MemoryBuffer> &Result,
uint64_t FileSize,
bool RequiresNullTerminator = true);
bool RequiresNullTerminator = true,
bool IsVolatile = false);
/// getMemBuffer - Open the specified memory range as a MemoryBuffer. Note
/// that InputData must be null terminated if RequiresNullTerminator is true.

50
lib/Support/MemoryBuffer.cpp
View File

@ -252,25 +252,29 @@ static error_code getMemoryBufferForStream(int FD,
static error_code getFileAux(const char *Filename,
std::unique_ptr<MemoryBuffer> &Result,
int64_t FileSize,
bool RequiresNullTerminator);
bool RequiresNullTerminator,
bool IsVolatile);
error_code MemoryBuffer::getFile(Twine Filename,
std::unique_ptr<MemoryBuffer> &Result,
int64_t FileSize,
bool RequiresNullTerminator) {
bool RequiresNullTerminator,
bool IsVolatile) {
// Ensure the path is null terminated.
SmallString<256> PathBuf;
StringRef NullTerminatedName = Filename.toNullTerminatedStringRef(PathBuf);
return getFileAux(NullTerminatedName.data(), Result, FileSize,
RequiresNullTerminator);
RequiresNullTerminator, IsVolatile);
}
error_code MemoryBuffer::getFile(Twine Filename,
OwningPtr<MemoryBuffer> &Result,
int64_t FileSize,
bool RequiresNullTerminator) {
bool RequiresNullTerminator,
bool IsVolatile) {
std::unique_ptr<MemoryBuffer> MB;
error_code ec = getFile(Filename, MB, FileSize, RequiresNullTerminator);
error_code ec = getFile(Filename, MB, FileSize, RequiresNullTerminator,
IsVolatile);
Result = std::move(MB);
return ec;
}
@ -278,18 +282,20 @@ error_code MemoryBuffer::getFile(Twine Filename,
static error_code getOpenFileImpl(int FD, const char *Filename,
std::unique_ptr<MemoryBuffer> &Result,
uint64_t FileSize, uint64_t MapSize,
int64_t Offset, bool RequiresNullTerminator);
int64_t Offset, bool RequiresNullTerminator,
bool IsVolatile);
static error_code getFileAux(const char *Filename,
std::unique_ptr<MemoryBuffer> &Result, int64_t FileSize,
bool RequiresNullTerminator) {
bool RequiresNullTerminator,
bool IsVolatile) {
int FD;
error_code EC = sys::fs::openFileForRead(Filename, FD);
if (EC)
return EC;
error_code ret = getOpenFileImpl(FD, Filename, Result, FileSize, FileSize, 0,
RequiresNullTerminator);
RequiresNullTerminator, IsVolatile);
close(FD);
return ret;
}
@ -348,7 +354,8 @@ static bool shouldUseMmap(int FD,
static error_code getOpenFileImpl(int FD, const char *Filename,
std::unique_ptr<MemoryBuffer> &Result,
uint64_t FileSize, uint64_t MapSize,
int64_t Offset, bool RequiresNullTerminator) {
int64_t Offset, bool RequiresNullTerminator,
bool IsVolatile) {
static int PageSize = sys::process::get_self()->page_size();
// Default is to map the full file.
@ -374,7 +381,8 @@ static error_code getOpenFileImpl(int FD, const char *Filename,
MapSize = FileSize;
}
if (shouldUseMmap(FD, FileSize, MapSize, Offset, RequiresNullTerminator,
if (!IsVolatile &&
shouldUseMmap(FD, FileSize, MapSize, Offset, RequiresNullTerminator,
PageSize)) {
error_code EC;
Result.reset(new (NamedBufferAlloc(Filename)) MemoryBufferMMapFile(
@ -428,33 +436,39 @@ static error_code getOpenFileImpl(int FD, const char *Filename,
error_code MemoryBuffer::getOpenFile(int FD, const char *Filename,
std::unique_ptr<MemoryBuffer> &Result,
uint64_t FileSize,
bool RequiresNullTerminator) {
bool RequiresNullTerminator,
bool IsVolatile) {
return getOpenFileImpl(FD, Filename, Result, FileSize, FileSize, 0,
RequiresNullTerminator);
RequiresNullTerminator, IsVolatile);
}
error_code MemoryBuffer::getOpenFile(int FD, const char *Filename,
OwningPtr<MemoryBuffer> &Result,
uint64_t FileSize,
bool RequiresNullTerminator) {
bool RequiresNullTerminator,
bool IsVolatile) {
std::unique_ptr<MemoryBuffer> MB;
error_code ec = getOpenFileImpl(FD, Filename, MB, FileSize, FileSize, 0,
RequiresNullTerminator);
RequiresNullTerminator, IsVolatile);
Result = std::move(MB);
return ec;
}
error_code MemoryBuffer::getOpenFileSlice(int FD, const char *Filename,
std::unique_ptr<MemoryBuffer> &Result,
uint64_t MapSize, int64_t Offset) {
return getOpenFileImpl(FD, Filename, Result, -1, MapSize, Offset, false);
uint64_t MapSize, int64_t Offset,
bool IsVolatile) {
return getOpenFileImpl(FD, Filename, Result, -1, MapSize, Offset, false,
IsVolatile);
}
error_code MemoryBuffer::getOpenFileSlice(int FD, const char *Filename,
OwningPtr<MemoryBuffer> &Result,
uint64_t MapSize, int64_t Offset) {
uint64_t MapSize, int64_t Offset,
bool IsVolatile) {
std::unique_ptr<MemoryBuffer> MB;
error_code ec = getOpenFileImpl(FD, Filename, MB, -1, MapSize, Offset, false);
error_code ec = getOpenFileImpl(FD, Filename, MB, -1, MapSize, Offset, false,
IsVolatile);
Result = std::move(MB);
return ec;
}