Skip to content

Commit

Permalink
[Support/MemoryBuffer] Introduce a boolean parameter (false by defaul…
Browse files Browse the repository at this point in the history 
…t) 'IsVolatile' for the open file functions.

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


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208007 91177308-0d34-0410-b5e6-96231b3b80d8
  • Loading branch information
@akyrtzi
akyrtzi committed May 5, 2014
1 parent 73ebb5a commit 32b6099
Show file tree
Hide file tree
Showing 2 changed files with 50 additions and 24 deletions.
24 changes: 18 additions & 6 deletions include/llvm/Support/MemoryBuffer.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -67,34 +67,46 @@ class MemoryBuffer {
/// 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.
Expand Down
50 changes: 32 additions & 18 deletions lib/Support/MemoryBuffer.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -252,44 +252,50 @@ 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;
}

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;
}
Expand Down Expand Up @@ -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.
Expand All @@ -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(
Expand Down Expand Up @@ -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;
}
Expand Down

0 comments on commit 32b6099

Please sign in to comment.