private static Interpreter getInterpreter(String contextId) throws EvalError {
// Get the appropriate interpreter
Interpreter i = null;
boolean createdInterp = false;
synchronized (interpreters) { // serialize two gets of the same name
i = interpreters.get(contextId);
if (i == null) {
i = new Interpreter();
interpreters.put(contextId, i);
createdInterp = true;
}
}
if (createdInterp) {
Log.log("Created context: " + contextId + " (" + i + ")");
// Now configure stdin and stdout to capture 10k of content
// Store references to the circular buffers within the interpreter itself.
// This provides a nice place to store them plus theoretically allows
// advanced use from within the bsh environment.
// On Windows print() outputs \r\n but in XQuery that's normalized to \n
// so the 10k of Java buffer may produce less than 10k of content in XQuery!
OutputStream circularOutput = new CircularByteArrayOutputStream(10240);
PrintStream printOutput = new PrintStream(circularOutput);
i.setOut(printOutput);
i.set("mljamout", circularOutput);
OutputStream circularError = new CircularByteArrayOutputStream(10240);
PrintStream printError = new PrintStream(circularError);
i.setErr(printError);
i.set("mljamerr", circularError);
// Capture the built-in System.out and System.err also.
// (Commented out since System appears global, can't do per interpreter.)
// i.set("mljamprintout", printOutput);
// i.set("mljamprinterr", printError);
// i.eval("System.setOut(mljamprintout);");
// i.eval("System.setErr(mljamprinterr);");
// Need to expose hexdecode() and base64decode() built-in functions
i.eval("hexdecode(String s) { return com.xqdev.jam.MLJAM.hexDecode(s); }");
i.eval("base64decode(String s) { return com.xqdev.jam.MLJAM.base64Decode(s); }");
// Let's tell the context what its id is
i.set("mljamid", contextId);
}
// Update the last accessed time, used for cleaning
i.set("mljamlast", System.currentTimeMillis());
// If it's been long enough, go snooping for stale contexts
if (System.currentTimeMillis() > lastClean + CLEAN_INTERVAL) {
Log.log("Initiated periodic scan for stale context objects");
lastClean = System.currentTimeMillis();
Iterator<Interpreter> itr = interpreters.values().iterator();
while (itr.hasNext()) {
Interpreter interp = itr.next();
Long last = (Long) interp.get("mljamlast");
if (System.currentTimeMillis() > last + STALE_TIMEOUT) {
itr.remove();
Log.log("Staled context: " + interp.get("mljamid") + " (" + interp + ")");
} else if ((System.currentTimeMillis() > last + TEMP_STALE_TIMEOUT)
&& ("" + interp.get("mljamid")).startsWith("temp:")) {
itr.remove();
Log.log("Staled temp context: " + interp.get("mljamid") + " (" + interp + ")");
}
}
}
return i;
}
protected void doPost(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
try {
// A good request looks like /mljam/contextid/verb?name=varname
// The extra path info includes the context id and verb
String extra = req.getPathInfo(); // "/contextid/verb"
if (extra == null || extra.equals("")) {
throw new ClientProblemException(
"Request requires a context id and verb in its extra path info");
}
String[] parts = extra.split("/"); // { "", "contextid", "verb" }
if (parts.length < 2) {
throw new ClientProblemException(
"Request requires a context id and verb in its extra path info");
} else if (parts.length < 3) {
throw new ClientProblemException("Request requires a verb in its extra path info");
}
String contextId = parts[1];
String verb = parts[2];
String method = req.getMethod();
if (method.equalsIgnoreCase("get")) {
// We have three GET verbs: get, get-stdout, get-stderr.
// These are all idempotent, while the POST verbs aren't. The get
// verb accept a "name" query string parameter. The get verb returns
// either XQuery to evaluate (indicated by x-marklogic/xquery content type)
// or a raw binary (indicated by an application/binary-encoded content type).
if (verb.equalsIgnoreCase("get")) {
String name = req.getParameter("name");
if (name == null || name.equals("")) {
throw new ClientProblemException("The get verb requires a name parameter");
}
Interpreter i = getInterpreter(contextId);
Object o = i.get(name);
if (o instanceof byte[]) {
sendBinaryResponse(res, (byte[]) o);
} else if (o instanceof String) {
sendStringResponse(res, (String) o);
} else {
sendXQueryResponse(res, o);
}
} else if (verb.equalsIgnoreCase("get-stdout")) {
Interpreter i = getInterpreter(contextId);
i.getOut().flush();
CircularByteArrayOutputStream circ = (CircularByteArrayOutputStream) i.get("mljamout");
if (circ != null) {
sendStringResponse(res, circ.toString());
circ.reset();
} else {
throw new ServerProblemException("Could not fetch mljamout from interpreter context");
}
} else if (verb.equalsIgnoreCase("get-stderr")) {
Interpreter i = getInterpreter(contextId);
i.getErr().flush();
CircularByteArrayOutputStream circ = (CircularByteArrayOutputStream) i.get("mljamerr");
if (circ != null) {
sendStringResponse(res, circ.toString());
circ.reset();
} else {
throw new ServerProblemException("Could not fetch mljamerr from interpreter context");
}
} else {
throw new ClientProblemException("Unrecognized GET verb: " + verb);
}
} else if (method.equalsIgnoreCase("post")) {
// We have six POST verbs: eval, unset, end, source, set-string, and set-binary.
// These are POST verbs because they aren't idempotent.
// The set-string, set-binary, unset, and source verbs accept a "name"
// query string parameter. The set-string and set-binary verbs accept
// a value in their post body. The eval verb accepts code in its post body.
if (verb.equalsIgnoreCase("set-string")) {
String name = req.getParameter("name");
if (name == null || name.equals("")) {
throw new ClientProblemException("The set-string verb requires a name parameter");
}
String body = getBody(req); // a value of "" is legit
Interpreter i = getInterpreter(contextId);
i.unset(name);
i.set(name, body);
sendNoResponse(res);
} else if (verb.equalsIgnoreCase("set-binary")) {
String name = req.getParameter("name");
if (name == null || name.equals("")) {
throw new ClientProblemException("The set-binary verb requires a name parameter");
}
String body = getBody(req); // a value of "" is legit
byte[] bodyBytes = hexDecode(body); // later could do this streaming for speed
Interpreter i = getInterpreter(contextId);
i.unset(name);
i.set(name, bodyBytes);
sendNoResponse(res);
} else if (verb.equalsIgnoreCase("eval")) {
String body = getBody(req);
if (body == null || body.equals("")) {
throw new ClientProblemException(
"The eval verb requires a post body containing code to eval");
}
Interpreter i = getInterpreter(contextId);
i.eval(body);
sendNoResponse(res);
} else if (verb.equalsIgnoreCase("eval-get")) {
String body = getBody(req);
if (body == null || body.equals("")) {
throw new ClientProblemException(
"The eval-get verb requires a post body containing code to eval");
}
Interpreter i = getInterpreter(contextId);
Object o = i.eval(body);
if (o instanceof byte[]) {
sendBinaryResponse(res, (byte[]) o);
} else if (o instanceof String) {
sendStringResponse(res, (String) o);
} else {
sendXQueryResponse(res, o);
}
} else if (verb.equalsIgnoreCase("unset")) {
String name = req.getParameter("name");
if (name == null || name.equals("")) {
throw new ClientProblemException("The unset verb requires a name parameter");
}
Interpreter i = getInterpreter(contextId);
i.unset(name);
sendNoResponse(res);
} else if (verb.equalsIgnoreCase("end")) {
endInterpreter(contextId);
sendNoResponse(res);
} else if (verb.equalsIgnoreCase("source")) {
String name = req.getParameter("name");
if (name == null || name.equals("")) {
throw new ClientProblemException("The source verb requires a name parameter");
}
Interpreter i = getInterpreter(contextId);
i.source(name);
sendNoResponse(res);
} else {
throw new ClientProblemException("Unrecognized POST verb: " + verb);
}
}
} catch (TargetError e) {
Throwable target = e.getTarget();
Log.log(e);
Log.log("Target: " + target);
sendServerProblemResponse(
res,
target.getClass().getName()
+ ": "
+ target.getMessage()
+ " when executing Java code: "
+ e.getErrorText()); // include full trace?
} catch (EvalError e) {
Log.log(e);
sendServerProblemResponse(
res, e.getClass().getName() + ": " + e.getMessage()); // include full trace?
} catch (ClientProblemException e) {
Log.log(e);
sendClientProblemResponse(res, e.getMessage());
} catch (ServerProblemException e) {
Log.log(e);
sendServerProblemResponse(res, e.getMessage());
}
}