[Fix #921] Caching resources

Signed-off-by: fjtirado <[email protected]>

Author: fjtirado

impl/core/src/main/java/io/serverlessworkflow/impl/WorkflowDefinition.java

@@ -149,5 +149,6 @@ public void addTaskExecutor(WorkflowMutablePosition position, TaskExecutor<?> ta
   @Override
   public void close() {
     safeClose(scheculedConsumer);
+    safeClose(resourceLoader);
   }
 }

impl/core/src/main/java/io/serverlessworkflow/impl/resources/ClasspathResource.java

@@ -16,6 +16,7 @@
 package io.serverlessworkflow.impl.resources;
 
 import java.io.InputStream;
+import java.util.Objects;
 
 public class ClasspathResource implements ExternalResourceHandler {
 
@@ -34,4 +35,18 @@ public InputStream open() {
   public String name() {
     return path;
   }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(path);
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (this == obj) return true;
+    if (obj == null) return false;
+    if (getClass() != obj.getClass()) return false;
+    ClasspathResource other = (ClasspathResource) obj;
+    return Objects.equals(path, other.path);
+  }
 }

impl/core/src/main/java/io/serverlessworkflow/impl/resources/DefaultResourceLoader.java

@@ -32,9 +32,8 @@
 import java.util.Map;
 import java.util.Optional;
 import java.util.ServiceLoader;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicReference;
-import java.util.concurrent.locks.Lock;
-import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.Function;
 
 public class DefaultResourceLoader implements ResourceLoader {
@@ -45,8 +44,7 @@ public class DefaultResourceLoader implements ResourceLoader {
   private final AtomicReference<URITemplateResolver> templateResolver =
       new AtomicReference<URITemplateResolver>();
 
-  private Map<ExternalResourceHandler, CachedResource> resourceCache = new LRUCache<>(100);
-  private Lock cacheLock = new ReentrantLock();
+  private Map<ExternalResourceHandler, CachedResource> resourceCache = new ConcurrentHashMap<>();
 
   protected DefaultResourceLoader(WorkflowApplication application, Path workflowPath) {
     this.application = application;
@@ -108,20 +106,15 @@ public <T> T load(
                     workflowContext,
                     taskContext,
                     model == null ? application.modelFactory().fromNull() : model));
-    try {
-      CachedResource<T> cachedResource;
-      cacheLock.lock();
-      cachedResource = resourceCache.get(resourceHandler);
-      cacheLock.unlock();
-      if (cachedResource == null || resourceHandler.shouldReload(cachedResource.lastReload())) {
-        cachedResource = new CachedResource(Instant.now(), function.apply(resourceHandler));
-        cacheLock.lock();
-        resourceCache.put(resourceHandler, cachedResource);
-      }
-      return cachedResource.content();
-    } finally {
-      cacheLock.unlock();
-    }
+    return (T)
+        resourceCache
+            .compute(
+                resourceHandler,
+                (k, v) ->
+                    v == null || resourceHandler.shouldReload(v.lastReload())
+                        ? new CachedResource(Instant.now(), function.apply(resourceHandler))
+                        : v)
+            .content();
   }
 
   @Override
@@ -169,4 +162,8 @@ public URI apply(WorkflowContext workflow, TaskContext task, WorkflowModel node)
       return URI.create(expr.apply(workflow, task, node));
     }
   }
+
+  public void close() {
+    resourceCache.clear();
+  }
 }

impl/core/src/main/java/io/serverlessworkflow/impl/resources/ExternalResourceHandler.java

@@ -24,7 +24,7 @@ public interface ExternalResourceHandler {
 
   InputStream open();
 
-  default boolean shouldReload(Instant lasUpdate) {
+  default boolean shouldReload(Instant lastUpdate) {
     return false;
   }
 }

impl/core/src/main/java/io/serverlessworkflow/impl/resources/FileResource.java

@@ -20,6 +20,9 @@
 import java.io.UncheckedIOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.attribute.BasicFileAttributes;
+import java.time.Instant;
+import java.util.Objects;
 
 class FileResource implements ExternalResourceHandler {
 
@@ -42,4 +45,30 @@ public InputStream open() {
   public String name() {
     return path.getFileName().toString();
   }
+
+  @Override
+  public boolean shouldReload(Instant lastUpdate) {
+    try {
+      return Files.readAttributes(path, BasicFileAttributes.class)
+          .lastModifiedTime()
+          .toInstant()
+          .isAfter(lastUpdate);
+    } catch (IOException e) {
+      throw new UncheckedIOException(e);
+    }
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(path);
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (this == obj) return true;
+    if (obj == null) return false;
+    if (getClass() != obj.getClass()) return false;
+    FileResource other = (FileResource) obj;
+    return Objects.equals(path, other.path);
+  }
 }

impl/core/src/main/java/io/serverlessworkflow/impl/resources/HttpResource.java

@@ -18,7 +18,10 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.UncheckedIOException;
+import java.net.HttpURLConnection;
 import java.net.URL;
+import java.time.Instant;
+import java.util.Objects;
 
 public class HttpResource implements ExternalResourceHandler {
 
@@ -40,4 +43,33 @@ public InputStream open() {
   public String name() {
     return url.getFile();
   }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(url);
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (this == obj) return true;
+    if (obj == null) return false;
+    if (getClass() != obj.getClass()) return false;
+    HttpResource other = (HttpResource) obj;
+    return Objects.equals(url, other.url);
+  }
+
+  @Override
+  public boolean shouldReload(Instant lastUpdate) {
+    try {
+      long millis = lastUpdate.toEpochMilli();
+      HttpURLConnection connection = (HttpURLConnection) url.openConnection();
+      connection.setUseCaches(true);
+      connection.setRequestMethod("HEAD");
+      connection.setIfModifiedSince(millis);
+      return connection.getResponseCode() != HttpURLConnection.HTTP_NOT_MODIFIED
+          && connection.getLastModified() > millis;
+    } catch (IOException e) {
+      throw new UncheckedIOException(e);
+    }
+  }
 }

impl/core/src/main/java/io/serverlessworkflow/impl/resources/LRUCache.java

@@ -24,7 +24,7 @@
 import java.net.URI;
 import java.util.function.Function;
 
-public interface ResourceLoader {
+public interface ResourceLoader extends AutoCloseable {
 
   WorkflowValueResolver<URI> uriSupplier(Endpoint endpoint);