Merge pull request bisq-network#4804 from chimp1984/improve-persisten…

…ce-manager

Improve persistence manager

common/src/main/java/bisq/common/persistence/PersistenceManager.java

@@ -44,6 +44,7 @@
 import java.util.Map;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.Consumer;
 
@@ -80,43 +81,59 @@ public class PersistenceManager<T extends PersistableEnvelope> {
     ///////////////////////////////////////////////////////////////////////////////////////////
 
     public static final Map<String, PersistenceManager<?>> ALL_PERSISTENCE_MANAGERS = new HashMap<>();
+    public static boolean FLUSH_ALL_DATA_TO_DISK_CALLED = false;
 
-    // We don't know from which thread we are called so we map back to user thread
+
+    // We require being called only once from the global shutdown routine. As the shutdown routine has a timeout
+    // and error condition where we call the method as well beside the standard path and it could be that those
+    // alternative code paths call our method after it was called already, so it is a valid but rare case.
+    // We add a guard to prevent repeated calls.
     public static void flushAllDataToDisk(ResultHandler completeHandler) {
-        log.info("Start flushAllDataToDisk at shutdown");
-        AtomicInteger openInstances = new AtomicInteger(ALL_PERSISTENCE_MANAGERS.size());
+        // We don't know from which thread we are called so we map to user thread
+        UserThread.execute(() -> {
+            if (FLUSH_ALL_DATA_TO_DISK_CALLED) {
+                log.warn("We got flushAllDataToDisk called again. This can happen in some rare cases. We ignore the repeated call.");
+                return;
+            }
 
-        if (openInstances.get() == 0) {
-            log.info("flushAllDataToDisk completed");
-            UserThread.execute(completeHandler::handleResult);
-        }
+            FLUSH_ALL_DATA_TO_DISK_CALLED = true;
+
+            log.info("Start flushAllDataToDisk at shutdown");
+            AtomicInteger openInstances = new AtomicInteger(ALL_PERSISTENCE_MANAGERS.size());
+
+            if (openInstances.get() == 0) {
+                log.info("No PersistenceManager instances have been created yet.");
+                completeHandler.handleResult();
+            }
 
-        new HashSet<>(ALL_PERSISTENCE_MANAGERS.values()).forEach(persistenceManager -> {
-            // For Priority.HIGH data we want to write to disk in any case to be on the safe side if we might have missed
-            // a requestPersistence call after an important state update. Those are usually rather small data stores.
-            // Otherwise we only persist if requestPersistence was called since the last persist call.
-            if (persistenceManager.source.flushAtShutDown || persistenceManager.persistenceRequested) {
-                // We don't know from which thread we are called so we map back to user thread when calling persistNow
-                UserThread.execute(() -> {
+            new HashSet<>(ALL_PERSISTENCE_MANAGERS.values()).forEach(persistenceManager -> {
+                // For Priority.HIGH data we want to write to disk in any case to be on the safe side if we might have missed
+                // a requestPersistence call after an important state update. Those are usually rather small data stores.
+                // Otherwise we only persist if requestPersistence was called since the last persist call.
+                if (persistenceManager.source.flushAtShutDown || persistenceManager.persistenceRequested) {
                     // We always get our completeHandler called even if exceptions happen. In case a file write fails
                     // we still call our shutdown and count down routine as the completeHandler is triggered in any case.
+
+                    // We get our result handler called from the write thread so we map back to user thread.
                     persistenceManager.persistNow(() ->
-                            onWriteCompleted(completeHandler, openInstances, persistenceManager));
-                });
-            } else {
-                onWriteCompleted(completeHandler, openInstances, persistenceManager);
-            }
+                            UserThread.execute(() -> onWriteCompleted(completeHandler, openInstances, persistenceManager)));
+                } else {
+                    onWriteCompleted(completeHandler, openInstances, persistenceManager);
+                }
+            });
         });
     }
 
+    // We get called always from user thread here.
     private static void onWriteCompleted(ResultHandler completeHandler,
                                          AtomicInteger openInstances,
                                          PersistenceManager<?> persistenceManager) {
         persistenceManager.shutdown();
         if (openInstances.decrementAndGet() == 0) {
             log.info("flushAllDataToDisk completed");
-            UserThread.execute(completeHandler::handleResult);
+            completeHandler.handleResult();
         }
+
     }
 
 
@@ -166,6 +183,7 @@ public enum Source {
     @Nullable
     private Timer timer;
     private ExecutorService writeToDiskExecutor;
+    public final AtomicBoolean initCalled = new AtomicBoolean(false);
 
 
     ///////////////////////////////////////////////////////////////////////////////////////////
@@ -190,6 +208,29 @@ public void initialize(T persistable, Source source) {
     }
 
     public void initialize(T persistable, String fileName, Source source) {
+        if (FLUSH_ALL_DATA_TO_DISK_CALLED) {
+            log.warn("We have started the shut down routine already. We ignore that initialize call.");
+            return;
+        }
+
+        if (ALL_PERSISTENCE_MANAGERS.containsKey(fileName)) {
+            RuntimeException runtimeException = new RuntimeException("We must not create multiple " +
+                    "PersistenceManager instances for file " + fileName + ".");
+            // We want to get logged from where we have been called so lets print the stack trace.
+            runtimeException.printStackTrace();
+            throw runtimeException;
+        }
+
+        if (initCalled.get()) {
+            RuntimeException runtimeException = new RuntimeException("We must not call initialize multiple times. " +
+                    "PersistenceManager for file: " + fileName + ".");
+            // We want to get logged from where we have been called so lets print the stack trace.
+            runtimeException.printStackTrace();
+            throw runtimeException;
+        }
+
+        initCalled.set(true);
+
         this.persistable = persistable;
         this.fileName = fileName;
         this.source = source;
@@ -233,6 +274,11 @@ public void readPersisted(Consumer<T> resultHandler, Runnable orElse) {
      * @param orElse            Called if no file exists or reading of file failed.
      */
     public void readPersisted(String fileName, Consumer<T> resultHandler, Runnable orElse) {
+        if (FLUSH_ALL_DATA_TO_DISK_CALLED) {
+            log.warn("We have started the shut down routine already. We ignore that readPersisted call.");
+            return;
+        }
+
         new Thread(() -> {
             T persisted = getPersisted(fileName);
             if (persisted != null) {
@@ -252,6 +298,11 @@ public T getPersisted() {
 
     @Nullable
     public T getPersisted(String fileName) {
+        if (FLUSH_ALL_DATA_TO_DISK_CALLED) {
+            log.warn("We have started the shut down routine already. We ignore that getPersisted call.");
+            return null;
+        }
+
         File storageFile = new File(dir, fileName);
         if (!storageFile.exists()) {
             return null;
@@ -288,6 +339,11 @@ public T getPersisted(String fileName) {
     ///////////////////////////////////////////////////////////////////////////////////////////
 
     public void requestPersistence() {
+        if (FLUSH_ALL_DATA_TO_DISK_CALLED) {
+            log.warn("We have started the shut down routine already. We ignore that requestPersistence call.");
+            return;
+        }
+
         persistenceRequested = true;
 
         // We write to disk with a delay to avoid frequent write operations. Depending on the priority those delays