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// Copyright 2014 The Bazel Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.devtools.build.lib.vfs;
import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
import com.google.devtools.build.lib.profiler.Profiler;
import com.google.devtools.build.lib.profiler.ProfilerTask;
import com.google.devtools.build.lib.unix.FileAccessException;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
/**
* This class implements the FileSystem interface using direct calls to the
* UNIX filesystem.
*/
@ThreadSafe
abstract class AbstractFileSystem extends FileSystem {
protected static final String ERR_PERMISSION_DENIED = " (Permission denied)";
protected static final Profiler profiler = Profiler.instance();
@Override
protected InputStream getInputStream(Path path) throws FileNotFoundException {
// This loop is a workaround for an apparent bug in FileInputStrean.open, which delegates
// ultimately to JVM_Open in the Hotspot JVM. This call is not EINTR-safe, so we must do the
// retry here.
for (;;) {
try {
return createFileInputStream(path);
} catch (FileNotFoundException e) {
if (e.getMessage().endsWith("(Interrupted system call)")) {
continue;
} else {
throw e;
}
}
}
}
/**
* Returns either normal or profiled FileInputStream.
*/
private InputStream createFileInputStream(Path path) throws FileNotFoundException {
final String name = path.toString();
if (profiler.isActive() && (profiler.isProfiling(ProfilerTask.VFS_READ) ||
profiler.isProfiling(ProfilerTask.VFS_OPEN))) {
long startTime = Profiler.nanoTimeMaybe();
try {
// Replace default FileInputStream instance with the custom one that does profiling.
return new FileInputStream(name) {
@Override public int read(byte b[]) throws IOException {
return read(b, 0, b.length);
}
@Override public int read(byte b[], int off, int len) throws IOException {
long startTime = Profiler.nanoTimeMaybe();
try {
return super.read(b, off, len);
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_READ, name);
}
}
};
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_OPEN, name);
}
} else {
// Use normal FileInputStream instance if profiler is not enabled.
return new FileInputStream(path.toString());
}
}
/**
* Returns either normal or profiled FileOutputStream. Should be used by subclasses
* to create default OutputStream instance.
*/
protected OutputStream createFileOutputStream(Path path, boolean append)
throws FileNotFoundException {
final String name = path.toString();
if (profiler.isActive() && (profiler.isProfiling(ProfilerTask.VFS_WRITE) ||
profiler.isProfiling(ProfilerTask.VFS_OPEN))) {
long startTime = Profiler.nanoTimeMaybe();
try {
return new FileOutputStream(name, append) {
@Override public void write(byte b[]) throws IOException {
write(b, 0, b.length);
}
@Override public void write(byte b[], int off, int len) throws IOException {
long startTime = Profiler.nanoTimeMaybe();
try {
super.write(b, off, len);
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_WRITE, name);
}
}
};
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_OPEN, name);
}
} else {
return new FileOutputStream(name, append);
}
}
@Override
protected OutputStream getOutputStream(Path path, boolean append) throws IOException {
synchronized (path) {
try {
return createFileOutputStream(path, append);
} catch (FileNotFoundException e) {
// Why does it throw a *FileNotFoundException* if it can't write?
// That does not make any sense! And its in a completely different
// format than in other situations, no less!
if (e.getMessage().equals(path + ERR_PERMISSION_DENIED)) {
throw new FileAccessException(e.getMessage());
}
throw e;
}
}
}
}
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