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-rw-r--r--xpcom/glue/FileUtils.h165
1 files changed, 165 insertions, 0 deletions
diff --git a/xpcom/glue/FileUtils.h b/xpcom/glue/FileUtils.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_FileUtils_h
+#define mozilla_FileUtils_h
+
+#include "nscore.h" // nullptr
+
+#if defined(XP_UNIX)
+# include <unistd.h>
+#elif defined(XP_WIN)
+# include <io.h>
+#endif
+#include "prio.h"
+#include "prlink.h"
+
+#include "mozilla/Scoped.h"
+#include "nsIFile.h"
+#include <errno.h>
+#include <limits.h>
+
+namespace mozilla {
+
+#if defined(XP_WIN)
+typedef void* filedesc_t;
+typedef const wchar_t* pathstr_t;
+#else
+typedef int filedesc_t;
+typedef const char* pathstr_t;
+#endif
+
+/**
+ * ScopedCloseFD is a RAII wrapper for POSIX file descriptors
+ *
+ * Instances |close()| their fds when they go out of scope.
+ */
+struct ScopedCloseFDTraits {
+ typedef int type;
+ static type empty() { return -1; }
+ static void release(type aFd) {
+ if (aFd != -1) {
+ close(aFd);
+ }
+ }
+};
+typedef Scoped<ScopedCloseFDTraits> ScopedClose;
+
+#if defined(MOZILLA_INTERNAL_API)
+
+/**
+ * AutoFDClose is a RAII wrapper for PRFileDesc.
+ *
+ * Instances |PR_Close| their fds when they go out of scope.
+ **/
+struct ScopedClosePRFDTraits {
+ typedef PRFileDesc* type;
+ static type empty() { return nullptr; }
+ static void release(type aFd) {
+ if (aFd) {
+ PR_Close(aFd);
+ }
+ }
+};
+typedef Scoped<ScopedClosePRFDTraits> AutoFDClose;
+
+/* RAII wrapper for FILE descriptors */
+struct ScopedCloseFileTraits {
+ typedef FILE* type;
+ static type empty() { return nullptr; }
+ static void release(type aFile) {
+ if (aFile) {
+ fclose(aFile);
+ }
+ }
+};
+typedef Scoped<ScopedCloseFileTraits> ScopedCloseFile;
+
+/**
+ * Fallocate efficiently and continuously allocates files via fallocate-type
+ * APIs. This is useful for avoiding fragmentation. On sucess the file be padded
+ * with zeros to grow to aLength.
+ *
+ * @param aFD file descriptor.
+ * @param aLength length of file to grow to.
+ * @return true on success.
+ */
+bool fallocate(PRFileDesc* aFD, int64_t aLength);
+
+/**
+ * Use readahead to preload shared libraries into the file cache before loading.
+ * WARNING: This function should not be used without a telemetry field trial
+ * demonstrating a clear performance improvement!
+ *
+ * @param aFile nsIFile representing path to shared library
+ */
+void ReadAheadLib(nsIFile* aFile);
+
+/**
+ * Use readahead to preload a file into the file cache before reading.
+ * WARNING: This function should not be used without a telemetry field trial
+ * demonstrating a clear performance improvement!
+ *
+ * @param aFile nsIFile representing path to shared library
+ * @param aOffset Offset into the file to begin preloading
+ * @param aCount Number of bytes to preload (SIZE_MAX implies file size)
+ * @param aOutFd Pointer to file descriptor. If specified, ReadAheadFile will
+ * return its internal, opened file descriptor instead of closing it.
+ */
+void ReadAheadFile(nsIFile* aFile, const size_t aOffset = 0,
+ const size_t aCount = SIZE_MAX,
+ filedesc_t* aOutFd = nullptr);
+
+/*
+ * Wrappers for PR_GetLibraryName and PR_GetLibraryFilePathname.
+ */
+PathString GetLibraryName(pathstr_t aDirectory, const char* aLib);
+PathString GetLibraryFilePathname(pathstr_t aName, PRFuncPtr aAddr);
+
+#endif // MOZILLA_INTERNAL_API
+
+/**
+ * Use readahead to preload shared libraries into the file cache before loading.
+ * WARNING: This function should not be used without a telemetry field trial
+ * demonstrating a clear performance improvement!
+ *
+ * @param aFilePath path to shared library
+ */
+void ReadAheadLib(pathstr_t aFilePath);
+
+/**
+ * Use readahead to preload a file into the file cache before loading.
+ * WARNING: This function should not be used without a telemetry field trial
+ * demonstrating a clear performance improvement!
+ *
+ * @param aFilePath path to shared library
+ * @param aOffset Offset into the file to begin preloading
+ * @param aCount Number of bytes to preload (SIZE_MAX implies file size)
+ * @param aOutFd Pointer to file descriptor. If specified, ReadAheadFile will
+ * return its internal, opened file descriptor instead of closing it.
+ */
+void ReadAheadFile(pathstr_t aFilePath, const size_t aOffset = 0,
+ const size_t aCount = SIZE_MAX,
+ filedesc_t* aOutFd = nullptr);
+
+/**
+ * Use readahead to preload a file into the file cache before reading.
+ * When this function exits, the file pointer is guaranteed to be in the same
+ * position it was in before this function was called.
+ * WARNING: This function should not be used without a telemetry field trial
+ * demonstrating a clear performance improvement!
+ *
+ * @param aFd file descriptor opened for read access
+ * (on Windows, file must be opened with FILE_FLAG_SEQUENTIAL_SCAN)
+ * @param aOffset Offset into the file to begin preloading
+ * @param aCount Number of bytes to preload (SIZE_MAX implies file size)
+ */
+void ReadAhead(filedesc_t aFd, const size_t aOffset = 0,
+ const size_t aCount = SIZE_MAX);
+
+} // namespace mozilla
+
+#endif