com.google.walkaround.util.client.log.ErrorReportingLogHandler.java Source code

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Here is the source code for com.google.walkaround.util.client.log.ErrorReportingLogHandler.java

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/*
 * Copyright 2011 Google Inc. 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.walkaround.util.client.log;

import com.google.gwt.core.client.GWT;
import com.google.gwt.core.client.JsonUtils;
import com.google.gwt.xhr.client.XMLHttpRequest;
import com.google.walkaround.util.client.log.Logs.Handler;
import com.google.walkaround.util.client.log.Logs.Level;

/**
 * A log handler that reports fatal logs to the server, and tees off warning
 * logs to its subclass.
 *
 * @author danilatos@google.com (Daniel Danilatos)
 */
public class ErrorReportingLogHandler implements Handler {
    private boolean firstReport = true;

    private final String errorReportUrl;

    public ErrorReportingLogHandler(String errorReportUrl) {
        this.errorReportUrl = errorReportUrl;
    }

    @Override
    public boolean canReceive() {
        return true;
    }

    @Override
    public void receiveEntry(int num, double timestamp, String stream, Level level, Object[] objects, Throwable t) {
        if (level.compareTo(Level.SEVERE) <= 0) {
            onSevere(stream);
            report(timestamp, stream, level, objects, t);
        }
    }

    /**
     * Notifies a subclass of a severe log event on a stream.
     */
    protected void onSevere(String stream) {
    }

    void report(double timestamp, String streamName, Level level, Object[] objects, Throwable t) {
        // TODO(danilatos): Use a JsoView to construct and then serialize, rather
        // than string builder, unless it's too slow (might even be faster).

        StringBuilder sb = new StringBuilder();
        sb.append("{\"strongName\" : ");
        sb.append(escape(GWT.getPermutationStrongName()));

        sb.append(",\"timestamp\" : ");
        sb.append("" + (long) timestamp);

        sb.append(",\"stream\" : ");
        sb.append(escape(streamName));

        sb.append(",\"level\" : ");
        sb.append(escape(level.name()));

        // Stacktrace info of the first exception found, if any
        if (t != null) {
            sb.append(",\"exception\" : ");
            buildExceptionJson(sb, t);
        }

        sb.append(",\"objects\" : [");
        boolean needsComma = false;
        for (Object o : objects) {
            if (needsComma) {
                sb.append(",");
            } else {
                needsComma = true;
            }
            sb.append(escape(o != null ? o.toString() : "(null)"));
        }

        sb.append("]}");
        String jsonData = sb.toString();

        XMLHttpRequest xhr = XMLHttpRequest.create();
        xhr.open("POST", errorReportUrl + "?firstReport=" + firstReport);
        firstReport = false;
        xhr.send(jsonData);
    }

    public void buildExceptionJson(StringBuilder sb, Throwable t) {
        sb.append("{\"name\" : ");
        sb.append(escape(t.getClass().getName()));

        sb.append(",\"message\" : ");
        sb.append(escape(t.getMessage()));

        sb.append(",\"stackTrace\" : [");
        boolean needsComma = false;
        for (StackTraceElement e : t.getStackTrace()) {
            if (needsComma) {
                sb.append(",");
            } else {
                needsComma = true;
            }

            sb.append(escape(e.getMethodName()));
        }
        sb.append("]");

        if (t.getCause() != null) {
            sb.append(",\"cause\" : ");
            buildExceptionJson(sb, t.getCause());
        }

        sb.append("}");
    }

    String escape(String unescaped) {
        // + "" to avoid null
        return JsonUtils.escapeValue(unescaped != null ? unescaped : "(null)");
    }
}