Allow polyglot embedders to control throwDeniedThreadAccess

sdk/src/org.graalvm.polyglot/src/org/graalvm/polyglot/Context.java

@@ -57,6 +57,7 @@
 import java.util.Map.Entry;
 import java.util.Objects;
 import java.util.concurrent.TimeoutException;
+import java.util.function.Consumer;
 import java.util.function.Predicate;
 import java.util.logging.Handler;
 import java.util.logging.Level;
@@ -286,8 +287,9 @@
  * instance may be used from multiple threads at the same time depends on if all initialized
  * languages support it. If initialized languages support multi-threading, then the context instance
  * may be used from multiple threads at the same time. If a context is used from multiple threads
- * and the language does not fit, then an {@link IllegalStateException} is thrown by the accessing
- * method.
+ * and the language does not fit, then an
+ * {@link IllegalStateException} is thrown by the accessing
+ * method (unless {@link Builder#onDeniedThreadAccess} is specified).
  * <p>
  * Meta-data from the context's underlying {@link #getEngine() engine} can be retrieved safely by
  * any thread at any time.
@@ -1060,6 +1062,7 @@ public final class Builder {
         private ClassLoader hostClassLoader;
         private boolean useSystemExit;
         private SandboxPolicy sandboxPolicy;
+        private Consumer<RuntimeException> onDeniedThreadAccess;
 
         Builder(String... permittedLanguages) {
             Objects.requireNonNull(permittedLanguages);
@@ -1180,6 +1183,23 @@ public Builder allowCreateThread(boolean enabled) {
             return this;
         }
 
+        /** Installs handler to control what happens on multiple thread access.
+         * When multiple threads are accessing a context which isn't ready for
+         * multithreaded access an exception is yielded by default. By installing
+         * this {@code handler} one can control what shall happen. Either to
+         * throw the provided exception or resolve the multithreaded situation
+         * and return to retry the thread access again.
+         *
+         * @param handler callback that either throws the provided {@code RuntimeException} or returns
+         *   to signal request for retry
+         * @return this builder
+         * @since 23.2
+         */
+        public Builder onDeniedThreadAccess(Consumer<RuntimeException> handler) {
+            this.onDeniedThreadAccess = handler;
+            return this;
+        }
+
         /**
          * Sets the default value for all privileges. If not explicitly specified, then all access
          * is <code>false</code>. If all access is enabled then certain privileges may still be
@@ -1935,7 +1955,7 @@ public Context build() {
             Object logHandler = customLogHandler != null ? Engine.getImpl().newLogHandler(customLogHandler) : null;
             String tmpDir = Engine.getImpl().getIO().hasHostFileAccess(useIOAccess) ? System.getProperty("java.io.tmpdir") : null;
             ctx = (Context) engine.dispatch.createContext(engine.receiver, useSandboxPolicy, contextOut, contextErr, contextIn, hostClassLookupEnabled,
-                            hostAccess, polyglotAccess, nativeAccess, createThread, hostClassLoading, innerContextOptions,
+                            hostAccess, polyglotAccess, nativeAccess, createThread, onDeniedThreadAccess, hostClassLoading, innerContextOptions,
                             experimentalOptions, localHostLookupFilter, contextOptions, arguments == null ? Collections.emptyMap() : arguments,
                             permittedLanguages, useIOAccess, logHandler, createProcess, processHandler, useEnvironmentAccess, environment, zone, limits,
                             localCurrentWorkingDirectory, tmpDir, hostClassLoader, allowValueSharing, useSystemExit);

sdk/src/org.graalvm.polyglot/src/org/graalvm/polyglot/impl/AbstractPolyglotImpl.java

@@ -807,7 +807,9 @@ public abstract Object createContext(Object receiver, SandboxPolicy sandboxPolic
                         Object hostAccess,
                         Object polyglotAccess,
                         boolean allowNativeAccess,
-                        boolean allowCreateThread, boolean allowHostClassLoading, boolean allowInnerContextOptions, boolean allowExperimentalOptions,
+                        boolean allowCreateThread,
+                        Consumer<RuntimeException> onDeniedThreadAccess,
+                        boolean allowHostClassLoading, boolean allowInnerContextOptions, boolean allowExperimentalOptions,
                         Predicate<String> classFilter,
                         Map<String, String> options,
                         Map<String, String[]> arguments, String[] onlyLanguages, Object ioAccess, Object logHandler, boolean allowCreateProcess, ProcessHandler processHandler,

truffle/src/com.oracle.truffle.api.test/src/com/oracle/truffle/api/test/wrapper/HostEngineDispatch.java

@@ -74,7 +74,8 @@ protected HostEngineDispatch(HostPolyglotDispatch polyglot) {
     @Override
     public Object createContext(Object receiver, SandboxPolicy sandboxPolicy, OutputStream out, OutputStream err, InputStream in, boolean allowHostAccess, Object hostAccess,
                     Object polyglotAccess,
-                    boolean allowNativeAccess, boolean allowCreateThread, boolean allowHostClassLoading, boolean allowInnerContextOptions, boolean allowExperimentalOptions,
+                    boolean allowNativeAccess, boolean allowCreateThread, Consumer<RuntimeException> onDeniedThreadAccess, boolean allowHostClassLoading, boolean allowInnerContextOptions,
+                    boolean allowExperimentalOptions,
                     Predicate<String> classFilter, Map<String, String> options, Map<String, String[]> arguments, String[] onlyLanguages, Object ioAccess, Object logHandler,
                     boolean allowCreateProcess, ProcessHandler processHandler, Object environmentAccess, Map<String, String> environment, ZoneId zone, Object limitsImpl,
                     String currentWorkingDirectory, String tmpDir, ClassLoader hostClassLoader, boolean allowValueSharing, boolean useSystemExit) {
@@ -83,6 +84,7 @@ public Object createContext(Object receiver, SandboxPolicy sandboxPolicy, Output
         AbstractEngineDispatch dispatch = api.getEngineDispatch(localEngine);
         Object engineReceiver = api.getEngineReceiver(localEngine);
         Context localContext = (Context) dispatch.createContext(engineReceiver, sandboxPolicy, out, err, in, allowHostAccess, hostAccess, polyglotAccess, allowNativeAccess, allowCreateThread,
+                        onDeniedThreadAccess,
                         allowHostClassLoading,
                         allowInnerContextOptions, allowExperimentalOptions, classFilter, options, arguments, onlyLanguages, ioAccess, logHandler, allowCreateProcess, processHandler,
                         environmentAccess, environment, zone, limitsImpl, currentWorkingDirectory, tmpDir, hostClassLoader, true, useSystemExit);

truffle/src/com.oracle.truffle.api.test/src/com/oracle/truffle/api/test/wrapper/HostEntryPoint.java

@@ -125,7 +125,7 @@ public long remoteCreateContext(long engineId, SandboxPolicy sandboxPolicy, Stri
         Object receiver = api.getEngineReceiver(engine);
         AbstractEngineDispatch dispatch = api.getEngineDispatch(engine);
         Context remoteContext = (Context) dispatch.createContext(receiver, sandboxPolicy, null, null, null, false, null, PolyglotAccess.NONE, false,
-                        false, false, false, false, null, new HashMap<>(), new HashMap<>(),
+                        false, null, false, false, false, null, new HashMap<>(), new HashMap<>(),
                         new String[0], IOAccess.NONE, null,
                         false, null, EnvironmentAccess.NONE,
                         null, null, null, null, tmpDir, null, true, false);

truffle/src/com.oracle.truffle.polyglot/src/com/oracle/truffle/polyglot/EngineAccessor.java

@@ -1095,7 +1095,7 @@ public TruffleContext createInternalContext(Object sourcePolyglotLanguageContext
             }
 
             PolyglotContextConfig innerConfig = new PolyglotContextConfig(engine, creatorConfig.sandboxPolicy, sharingEnabled, useOut, useErr, useIn,
-                            useAllowHostLookup, usePolyglotAccess, useAllowNativeAccess, useAllowCreateThread, useAllowHostClassLoading,
+                            useAllowHostLookup, usePolyglotAccess, useAllowNativeAccess, useAllowCreateThread, creatorConfig.onDeniedThreadAccess, useAllowHostClassLoading,
                             useAllowInnerContextOptions, creatorConfig.allowExperimentalOptions,
                             useClassFilter, useArguments, allowedLanguages, useOptions, fileSystemConfig, creatorConfig.logHandler,
                             useAllowCreateProcess, useProcessHandler, useEnvironmentAccess, useCustomEnvironment,
@@ -1150,7 +1150,14 @@ public Thread createThread(Object polyglotLanguageContext, Runnable runnable, Ob
                 threadContext = innerContext.getContext(threadContext.language);
             }
             PolyglotThread newThread = new PolyglotThread(threadContext, runnable, group, stackSize, beforeEnter, afterLeave);
-            threadContext.context.checkMultiThreadedAccess(newThread);
+            for (;;) {
+                try {
+                    threadContext.context.checkMultiThreadedAccess(newThread);
+                    break;
+                } catch (PolyglotThreadAccessException ex) {
+                    ex.rethrow(threadContext.context);
+                }
+            }
             return newThread;
         }
 

truffle/src/com.oracle.truffle.polyglot/src/com/oracle/truffle/polyglot/PolyglotContextConfig.java

@@ -109,6 +109,7 @@ final class PolyglotContextConfig {
     final Runnable onCancelled;
     final Consumer<Integer> onExited;
     final Runnable onClosed;
+    final Consumer<RuntimeException> onDeniedThreadAccess;
 
     /**
      * Groups PolyglotContext's filesystem related configurations.
@@ -231,6 +232,7 @@ private static Map<String, String> computeCommonOptions(Map<String, String> opti
                         sharableConfig.polyglotAccess == null ? engine.getAPIAccess().getPolyglotAccessAll() : sharableConfig.polyglotAccess,
                         sharableConfig.nativeAccessAllowed,
                         sharableConfig.createThreadAllowed,
+                        null,
                         false,
                         false,
                         false,
@@ -256,7 +258,7 @@ private static Map<String, String> computeCommonOptions(Map<String, String> opti
     PolyglotContextConfig(PolyglotEngineImpl engine, SandboxPolicy sandboxPolicy, Boolean forceSharing,
                     OutputStream out, OutputStream err, InputStream in,
                     boolean hostLookupAllowed, Object polyglotAccess, boolean nativeAccessAllowed,
-                    boolean createThreadAllowed, boolean hostClassLoadingAllowed,
+                    boolean createThreadAllowed, Consumer<RuntimeException> onDeniedThreadAccess, boolean hostClassLoadingAllowed,
                     boolean contextOptionsAllowed, boolean allowExperimentalOptions,
                     Predicate<String> classFilter, Map<String, String[]> applicationArguments,
                     Set<String> onlyLanguages, Map<String, String> options, FileSystemConfig fileSystemConfig, LogHandler logHandler,
@@ -278,6 +280,7 @@ private static Map<String, String> computeCommonOptions(Map<String, String> opti
         this.polyglotAccess = polyglotAccess;
         this.nativeAccessAllowed = nativeAccessAllowed;
         this.createThreadAllowed = createThreadAllowed;
+        this.onDeniedThreadAccess = onDeniedThreadAccess;
         this.hostClassLoadingAllowed = hostClassLoadingAllowed;
         this.innerContextOptionsAllowed = contextOptionsAllowed;
         this.allowExperimentalOptions = allowExperimentalOptions;