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package il.ac.bgu.cs.bp.bpjs.model;
import il.ac.bgu.cs.bp.bpjs.execution.jsproxy.BProgramJsProxy;
import il.ac.bgu.cs.bp.bpjs.model.eventselection.EventSelectionStrategy;
import il.ac.bgu.cs.bp.bpjs.model.eventselection.SimpleEventSelectionStrategy;
import java.util.*;
import java.util.concurrent.*;
import il.ac.bgu.cs.bp.bpjs.exceptions.BPjsCodeEvaluationException;
import il.ac.bgu.cs.bp.bpjs.exceptions.BPjsException;
import il.ac.bgu.cs.bp.bpjs.exceptions.BPjsRuntimeException;
import il.ac.bgu.cs.bp.bpjs.execution.jsproxy.BpLog;
import il.ac.bgu.cs.bp.bpjs.execution.tasks.FailedAssertionException;
import il.ac.bgu.cs.bp.bpjs.internal.ScriptableUtils;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;
import org.mozilla.javascript.Context;
import org.mozilla.javascript.ContextFactory;
import org.mozilla.javascript.ImporterTopLevel;
import org.mozilla.javascript.Scriptable;
import java.util.concurrent.atomic.AtomicInteger;
import org.mozilla.javascript.EcmaError;
import org.mozilla.javascript.EvaluatorException;
import org.mozilla.javascript.WrappedException;
/**
* Base class for BPrograms. Provides the context (JavaScript scope, external
* event queue, etc.) b-threads interact with while running. Concrete BProgram
* extend this class by implementing the
* {@link #setupProgramScope(org.mozilla.javascript.Scriptable)} method.
*
* For creating a BProgram that uses a single JavaScript file available in the
* classpath, see {@link ResourceBProgram}. For creating them from a
* hard-coded string, see {@link StringBProgram}.
*
* @author michael
*/
public abstract class BProgram {
// ------------- Static Members ---------------
/**
* "Poison pill" to insert to the external event queue. Used only to turn
* the wait-for-external-events mode off.
*/
static final BEvent NO_MORE_WAIT_EXTERNAL = new BEvent("___bpjs-internal____NO_MORE_WAIT_EXTERNAL");
/**
* Counter for giving anonymous instances some semantic name.
*/
private static final AtomicInteger INSTANCE_COUNTER = new AtomicInteger();
/**
* A callback interface invoked when a b-thread is added to {@code this}.
*/
public interface BProgramCallback {
void bthreadAdded(BProgram bp, BThreadSyncSnapshot theBThread);
}
// ------------- Instance Members ---------------
private String name;
/**
* When {@code true}, the BProgram waits for an external event when no
* internal ones are available. Corollary: the program does not terminate at
* the end of a super-step.
*/
private boolean waitForExternalEvents;
/**
* Events are enqueued here by external threads
*/
private final BlockingQueue recentlyEnqueuedExternalEvents = new LinkedBlockingQueue<>();
/**
* BThreads added between syncs are added here.
*/
private final BlockingQueue recentlyRegisteredBthreads = new LinkedBlockingDeque<>();
private final BlockingQueue recentlyAddedForks = new LinkedBlockingDeque<>();
private volatile boolean started = false;
protected Scriptable programScope;
private EventSelectionStrategy eventSelectionStrategy;
private BProgramJsProxy jsProxy;
private BpLog.LogLevel preSetLogLevel = null;
/**
* Objects that client code wishes to put in scope before the scope is
* initialized are collected here.
*/
protected Map initialScopeValues = new HashMap<>();
private Optional addBThreadCallback = Optional.empty();
private List appendedCode;
private List prependedCode;
/**
* Constructs a BProgram with a default name, guaranteed to be unique within
* a given run.
*/
public BProgram() {
this("BProgram-" + INSTANCE_COUNTER.incrementAndGet());
}
/**
* Constructs a BProgram with a specific name.
*
* @param aName name for the new BProgram.
*/
public BProgram(String aName) {
name = aName;
}
/**
* Creates a BProgram with a specific name and an event selection strategy.
*
* @param aName Name for the program.
* @param anEss Event selection strategy.
*/
public BProgram(String aName, EventSelectionStrategy anEss) {
name = aName;
eventSelectionStrategy = anEss;
}
/**
* Adds more source code to be evaluated after
* {@link #setupProgramScope(org.mozilla.javascript.Scriptable)} is called.
* This method allows to programatically add code, e.g. for adding standard
* environment, mocking non-modeled parts for model-checking.
*
* @throws IllegalStateException if the code is appended after the bprogram
* started.
* @param source JavaScript source to be added at the end of the current source.
*/
public void appendSource(String source) {
if (started) {
throw new IllegalStateException("Cannot append code after the program had started.");
} else {
if (appendedCode == null) {
appendedCode = new ArrayList<>();
}
appendedCode.add(source);
}
}
/**
* Adds more source code to be evaluated before
* {@link #setupProgramScope(org.mozilla.javascript.Scriptable)} is called.
* This method allows to programatically add code, e.g. for adding standard
* environment, mocking non-modeled parts for model-checking.
*
* @throws IllegalStateException if the code is appended after the bprogram
* started.
* @param source JavaScript source to be added at the beginning of the current source.
*/
public void prependSource(String source) {
if (started) {
throw new IllegalStateException("Cannot append code after the program had started.");
} else {
if (prependedCode == null) {
prependedCode = new ArrayList<>();
}
prependedCode.add(source);
}
}
/**
* Reads and evaluates the code at the passed input stream. The stream is
* read to its end, but is not closed.
*
* @param inStrm Input stream for reading the script to be evaluated.
* @param scriptName for error reporting purposes.
* @return Result of evaluating the code at {@code inStrm}.
*/
protected Object evaluate(InputStream inStrm, String scriptName) {
InputStreamReader streamReader = new InputStreamReader(inStrm, StandardCharsets.UTF_8);
BufferedReader br = new BufferedReader(streamReader);
StringBuilder sb = new StringBuilder();
String line;
try {
while ((line = br.readLine()) != null) {
sb.append(line).append("\n");
}
} catch (IOException e) {
throw new RuntimeException("error while reading javascript from stream", e);
}
String script = sb.toString();
return evaluate(script, scriptName);
}
/**
* Runs the passed code in the passed scope.
*
* @param script Code to evaluate
* @param scriptName For error reporting purposes.
* @return Result of code evaluation.
*/
protected Object evaluate(String script, String scriptName) {
try {
Context curCtx = Context.getCurrentContext();
curCtx.setLanguageVersion(Context.VERSION_1_8);
return curCtx.evaluateString(programScope, script, scriptName, 1, null);
} catch (EcmaError rerr) {
throw new BPjsCodeEvaluationException(rerr);
} catch (WrappedException wrapped) {
try {
throw wrapped.getCause();
} catch (BPjsException be ) {
throw be;
} catch ( IllegalStateException ise ) {
String msg = ise.getMessage();
if ( msg.contains("Cannot capture continuation") && msg.contains("executeScriptWithContinuations or callFunctionWithContinuations") ){
throw new BPjsCodeEvaluationException("bp.sync called outside of a b-thread");
} else {
throw ise;
}
} catch ( Throwable generalException ) {
throw new BPjsRuntimeException("(Wrapped) Exception evaluating BProgram code: " + generalException.getMessage(), generalException);
}
} catch (EvaluatorException evalExp) {
throw new BPjsCodeEvaluationException(evalExp);
} catch ( Exception exp ) {
throw new BPjsRuntimeException("Error evaluating BProgram code: " + exp.getMessage(), exp);
}
}
/**
* Registers a BThread into the program. If the program started, the BThread
* will take part in the current bstep.
*
* @param bt the BThread to be registered.
*/
public void registerBThread(BThreadSyncSnapshot bt) {
recentlyRegisteredBthreads.add(bt);
addBThreadCallback.ifPresent(cb -> cb.bthreadAdded(this, bt));
}
void registerForkedChild( BThreadSyncSnapshot btss ) {
// make the top-level scope be *this* program's programScope
Scriptable pus = ScriptableUtils.getPenultiamteParent(btss.getScope());
pus.setParentScope(programScope);
addBThreadCallback.ifPresent(cb -> cb.bthreadAdded(this, btss));
}
/**
* Adds an event to {@code this}' external event queue.
*
* @param e The event to add.
*/
public void enqueueExternalEvent(BEvent e) {
recentlyEnqueuedExternalEvents.add(e);
}
/**
* Sets up the program scope and evaluates the program source.
*
* This method can only be called once per instance.
*
* @return a snapshot of the program, after source code was executed, and
* before any registered b-threads have run.
* @throws IllegalStateException for repeated calls.
*/
public BProgramSyncSnapshot setup() {
if (started) {
throw new IllegalStateException("Program already set up.");
}
Set bthreads = drainRecentlyRegisteredBthreads();
if (eventSelectionStrategy == null) {
eventSelectionStrategy = new SimpleEventSelectionStrategy();
}
FailedAssertion failedAssertion = null;
try {
Context cx = ContextFactory.getGlobal().enterContext();
cx.setOptimizationLevel(-1); // must use interpreter mode
initProgramScope(cx);
// evaluate code in order
if (prependedCode != null) {
prependedCode.forEach(s -> evaluate(s, "prependedCode"));
prependedCode = null;
}
setupProgramScope(programScope);
if (appendedCode != null) {
appendedCode.forEach(s -> evaluate(s, "appendedCode"));
appendedCode = null;
}
} catch (FailedAssertionException fae) {
failedAssertion = new FailedAssertion(fae.getMessage(), "---init_code");
} finally {
Context.exit();
}
started = true;
return new BProgramSyncSnapshot(this, bthreads, Collections.emptyList(), failedAssertion);
}
private void initProgramScope(Context cx) {
// load and execute globalScopeInit.js
ImporterTopLevel importer = new ImporterTopLevel(cx);
programScope = cx.initStandardObjects(importer);
jsProxy = new BProgramJsProxy(this);
if ( preSetLogLevel != null ) {
jsProxy.log.setLevel(preSetLogLevel.name());
}
programScope.put("bp", programScope, Context.javaToJS(jsProxy, programScope));
// evaluateResource("globalScopeInit.js");// <-- Currently not needed. Leaving in as we might need it soon.
initialScopeValues.entrySet().forEach(e -> putInGlobalScope(e.getKey(), e.getValue()));
initialScopeValues = null;
}
/**
* The BProgram should set up its scope here. Normally, this amounts to
* loading the script with the BThreads.
*
* @param scope the scope to set up.
*/
protected abstract void setupProgramScope(Scriptable scope);
/**
* Blocks until an external event is added. Then, if that event is not the
* "stop daemon mode" one, returns the event. Otherwise, returns
* {@code null}.
*
* @return The event, or {@code null} in case the daemon mode is turned off
* during the wait.
* @throws InterruptedException (blocking call, we have to do this)
*/
public BEvent takeExternalEvent() throws InterruptedException {
BEvent next = recentlyEnqueuedExternalEvents.take();
if (next == NO_MORE_WAIT_EXTERNAL) {
waitForExternalEvents = false;
return null;
} else {
return next;
}
}
/**
* Sets whether this program waits for external events or not.
*
* When set to {@code false}, when no events are available for selection,
* the program terminates.
*
* @param shouldWait {@code true} causes the system to wait for external events. {@code false} causes it to not wait.
*/
public void setWaitForExternalEvents(boolean shouldWait) {
if (waitForExternalEvents && !shouldWait) {
waitForExternalEvents = false;
recentlyEnqueuedExternalEvents.add(NO_MORE_WAIT_EXTERNAL);
} else {
waitForExternalEvents = shouldWait;
}
}
/**
* Returns {@code true} iff the program waits for external events. When
* {@code true}, the program will not terminate when it has no event
* available for selection. Rather, it will wait for an external event to be
* enqueued into its external event queue.
*
* @return {@code true} if this BProgram waits for external events,
* {@code false} otherwise.
* @see #enqueueExternalEvent(il.ac.bgu.cs.bp.bpjs.model.BEvent)
*/
public boolean isWaitForExternalEvents() {
return waitForExternalEvents;
}
/**
* Returns the program's global scope.
*
* @return the global scope of the program.
*/
public Scriptable getGlobalScope() {
return programScope;
}
/**
* Adds an object to the program's global scope. JS code can reference the
* added object by {@code name}.
*
* @param name The name under which {@code object} will be available to the
* JS code.
* @param obj The object to be added to the program's scope.
*/
public void putInGlobalScope(String name, Object obj) {
if (getGlobalScope() == null) {
initialScopeValues.put(name, obj);
} else {
try {
Context.enter();
getGlobalScope().put(name, programScope, Context.javaToJS(obj, programScope));
} finally {
Context.exit();
}
}
}
/**
* Gets the object pointer by the passed name in the global scope.
*
* @param Class of the returned object.
* @param name Name of the object in the JS heap.
* @param clazz Class of the returned object
* @return The object pointer by the passed name in the JS heap, converted
* to the passed class.
*/
public Optional getFromGlobalScope(String name, Class clazz) {
if (getGlobalScope().has(name, programScope)) {
return Optional.of((T) Context.jsToJava(getGlobalScope().get(name, getGlobalScope()), clazz));
} else {
return Optional.empty();
}
}
/**
* Sets the name of the program
*
* @param name the new program's name
*/
public void setName(String name) {
this.name = name;
}
/**
* @return the program's name
*/
public String getName() {
return name;
}
Set drainRecentlyRegisteredBthreads() {
Set out = new HashSet<>();
recentlyRegisteredBthreads.drainTo(out);
return out;
}
List drainEnqueuedExternalEvents() {
List out = new ArrayList<>(recentlyEnqueuedExternalEvents.size());
recentlyEnqueuedExternalEvents.drainTo(out);
return out;
}
void addFork( ForkStatement fkStmt ) {
recentlyAddedForks.add(fkStmt);
}
Set drainRecentlyAddedForks() {
Set out = new HashSet<>();
recentlyAddedForks.drainTo(out);
return out;
}
public void setAddBThreadCallback(BProgramCallback anAddBThreadCallback) {
addBThreadCallback = Optional.ofNullable(anAddBThreadCallback);
}
public EventSelectionStrategy getEventSelectionStrategy() {
if (eventSelectionStrategy == null) {
setEventSelectionStrategy(new SimpleEventSelectionStrategy());
}
return eventSelectionStrategy;
}
/**
* Sets the event selection strategy to be used.
* @param Actual type of the strategy
* @param anEventSelectionStrategy the strategy
* @return the strategy (so it can be cleanly assigned to a variable).
*/
public T setEventSelectionStrategy(T anEventSelectionStrategy) {
eventSelectionStrategy = anEventSelectionStrategy;
return anEventSelectionStrategy;
}
public void setLogLevel( BpLog.LogLevel aLevel ) {
if ( jsProxy != null ) {
jsProxy.log.setLevel(aLevel.name());
} else {
preSetLogLevel = aLevel;
}
}
public BpLog.LogLevel getLogLevel() {
return (jsProxy != null ) ? BpLog.LogLevel.valueOf(jsProxy.log.getLevel()) : null;
}
@Override
public String toString() {
return "[BProgram " + getName() + "]";
}
}
