/**
* Sends the given message as a PNG image. <strong>This method will block</strong> while image is
* being generated. It's only recommended for cases where we want to report an error back to the
* user and the user's browser expects a PNG image. Don't abuse it.
*
* @param status The status of the request (e.g. 200 OK or 404 Not Found).
* @param msg The message to send as an image.
* @param max_age The expiration time of this entity, in seconds. This is not a timestamp, it's
* how old the resource is allowed to be in the client cache. See RFC 2616 section 14.9 for
* more information. Use 0 to disable caching.
*/
public void sendAsPNG(final HttpResponseStatus status, final String msg, final int max_age) {
try {
final long now = System.currentTimeMillis() / 1000;
Plot plot = new Plot(now - 1, now);
HashMap<String, String> params = new HashMap<String, String>(1);
StringBuilder buf = new StringBuilder(1 + msg.length() + 18);
buf.append('"');
escapeJson(msg, buf);
buf.append("\" at graph 0.02,0.97");
params.put("label", buf.toString());
buf = null;
plot.setParams(params);
params = null;
final String basepath =
RpcHandler.getDirectoryFromSystemProp("tsd.http.cachedir")
+ Integer.toHexString(msg.hashCode());
GraphHandler.runGnuplot(this, basepath, plot);
plot = null;
sendFile(status, basepath + ".png", max_age);
} catch (Exception e) {
getQueryString().remove("png"); // Avoid recursion.
internalError(
new RuntimeException(
"Failed to generate a PNG with the" + " following message: " + msg, e));
}
}
private static List<Integer> doTopologicalSort(Graph<Coordinate, Street> g) {
final GraphHandler<Coordinate, Street> handler = new GraphHandler<Coordinate, Street>(g, true);
GraphSearchProcessor gsp =
new GraphSearchProcessor<Coordinate, Street>() {
Stack<Integer> stack = new Stack();
boolean foundCycle = false;
@Override
public void processVertexEarly(Graph<Coordinate, Street> graph, int vID) {}
@Override
public void processEdge(
Graph<Coordinate, Street> graph, int eID, int vIDfrom, int vIDto) {
if (handler.getVertexState(vIDto) == GraphHandler.DiscoverState.DISCOVERED) {
// We have found a cycle and need to abort!
handler.stopSearch();
foundCycle = true;
}
}
@Override
public void processVertexLate(Graph<Coordinate, Street> graph, int vID) {
stack.push(vID);
}
@Override
public Object getResults() {
ArrayList<Integer> topSortOrder = new ArrayList<Integer>();
if (foundCycle) return topSortOrder;
while (!stack.isEmpty()) topSortOrder.add(stack.pop());
return topSortOrder;
}
};
handler.addGraphSearchProcessor(gsp);
handler.doExhaustiveDFS();
ArrayList<Integer> ret = (ArrayList<Integer>) gsp.getResults();
return ret;
}
