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// Copyright 2017 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.worker;
import static java.nio.charset.StandardCharsets.UTF_8;
import com.google.auto.value.AutoValue;
import com.google.common.base.Preconditions;
import com.google.common.base.Throwables;
import com.google.devtools.build.lib.vfs.FileSystemUtils;
import com.google.devtools.build.lib.vfs.Path;
import java.io.IOException;
/** A well-formatted error message that is easy to read and easy to create. */
@AutoValue
abstract class ErrorMessage {
abstract String message();
@Override
public String toString() {
return message();
}
public static Builder builder() {
return new Builder();
}
public static final class Builder {
private String message = "Unknown error";
private Path logFile;
private String logText = "";
private int logSizeLimit = Integer.MAX_VALUE;
private Exception exception;
private Builder() {}
/** Sets the main text of this error message. */
public Builder message(String message) {
Preconditions.checkNotNull(message);
this.message = message.isEmpty() ? "Unknown error" : message.trim();
return this;
}
/** Sets the log file that should be printed as part of the error message. */
public Builder logFile(Path logFile) {
Preconditions.checkNotNull(logFile);
try {
this.logFile = logFile;
return logText(FileSystemUtils.readContent(logFile, UTF_8));
} catch (IOException e) {
logSizeLimit(Integer.MAX_VALUE);
return logText(
"ERROR: IOException while trying to read log file:\n"
+ Throwables.getStackTraceAsString(e));
}
}
/**
* Sets additional text, which is to be presented as a log file in the error message.
*
* <p>If the log originally comes from a file, it is recommended to use {@link #logFile}
* instead, because then the path to the log file can be printed together with the message.
*/
public Builder logText(String logText) {
Preconditions.checkNotNull(logText);
// Set the log text to "(empty)" when the passed in string is empty, otherwise error messages
// like "Something failed. Check below log for details:" would be pretty confusing for users.
this.logText = logText.isEmpty() ? "(empty)" : logText.trim();
return this;
}
/**
* If the log file or text of this error message is longer than the character limit set via this
* method, it will be truncated so that only the last X characters of the log are printed.
*/
public Builder logSizeLimit(int logSizeLimit) {
Preconditions.checkArgument(logSizeLimit > 0, "logSizeLimit must be positive");
this.logSizeLimit = logSizeLimit;
return this;
}
/** Lets the error message contain the details of an exception. */
public Builder exception(Exception e) {
this.exception = e;
return this;
}
/** Builds and returns the formatted error message. */
public ErrorMessage build() {
StringBuilder sb = new StringBuilder(message);
if (exception != null) {
sb.append("\n\n---8<---8<--- Exception details ---8<---8<---\n");
sb.append(Throwables.getStackTraceAsString(exception).trim());
sb.append("\n---8<---8<--- End of exception details ---8<---8<---");
}
if (!logText.isEmpty()) {
sb.append("\n\n---8<---8<--- Start of log");
if (logText.length() > logSizeLimit) {
sb.append(" snippet");
}
if (logFile != null) {
sb.append(", file at ");
sb.append(logFile.getPathString());
}
sb.append(" ---8<---8<---\n");
// If the length of the log is longer than the limit, print only the last part.
if (logText.length() > logSizeLimit) {
sb.append("[... truncated ...]\n");
sb.append(logText, logText.length() - logSizeLimit, logText.length());
sb.append("\n---8<---8<--- End of log snippet, ");
sb.append(logText.length() - logSizeLimit);
sb.append(" chars omitted ---8<---8<---");
} else {
sb.append(logText);
sb.append("\n---8<---8<--- End of log ---8<---8<---");
}
}
return new AutoValue_ErrorMessage(sb.toString());
}
}
}
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