feat: add TxWatcher (#99)

* support spring tx

* Revert "support spring tx"

This reverts commit 94dd068.

* feat: add TxWatcher (#98)

* fix: add the new usage to README.md

README.md

@@ -77,6 +77,9 @@ casbin:
   #CasbinWatcher notification mode, defaults to use Redis for notification synchronization, temporarily only supports Redis
   #After opening Watcher, you need to manually add spring-boot-starter-data-redis dependency.
   watcherType: redis
+  #Watcher to support spring tx, the default is not enable.
+  #If the mechanism is enabled, When updating policy in a spring transaction, watcher will trigger the update after commit
+  watcherTxSupport: false
   exception:
     ... See Schedule A for exception settings.
 ```

src/main/java/org/casbin/spring/boot/autoconfigure/CasbinRedisWatcherAutoConfiguration.java

@@ -12,11 +12,13 @@
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnExpression;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration;
 import org.springframework.boot.autoconfigure.data.redis.RedisProperties;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Primary;
 import org.springframework.data.redis.core.RedisTemplate;
 
 /**
@@ -71,4 +73,15 @@ public Watcher lettuceRedisWatcher(RedisProperties redisProperties, CasbinProper
             throw new CasbinWatcherLettuceTypeUnsupportedException("Unsupported watcher type!");
         }
     }
-}
+
+    @Bean
+    @Primary
+    @ConditionalOnBean(Watcher.class)
+    @ConditionalOnProperty(value = "casbin.watcher-tx-support", havingValue = "true")
+    public Watcher txWatcher(Watcher watcher, Enforcer enforcer) {
+        TxWatcher txWatcher = new TxWatcher(watcher);
+        enforcer.setWatcher(txWatcher);
+        logger.info("TxWatcher proxy watcher: {}", watcher.getClass().getName());
+        return txWatcher;
+    }
+}

src/main/java/org/casbin/spring/boot/autoconfigure/TxWatcher.java

@@ -0,0 +1,41 @@
+package org.casbin.spring.boot.autoconfigure;
+
+import org.casbin.jcasbin.persist.Watcher;
+import org.springframework.transaction.support.TransactionSynchronization;
+
+import java.util.function.Consumer;
+
+import static org.springframework.transaction.support.TransactionSynchronizationManager.isActualTransactionActive;
+import static org.springframework.transaction.support.TransactionSynchronizationManager.registerSynchronization;
+
+public class TxWatcher implements Watcher {
+    private final Watcher watcher;
+
+    public TxWatcher(Watcher watcher) {
+        this.watcher = watcher;
+    }
+
+    @Override
+    public void setUpdateCallback(Runnable runnable) {
+        this.watcher.setUpdateCallback(runnable);
+    }
+
+    @Override
+    public void setUpdateCallback(Consumer<String> consumer) {
+        this.watcher.setUpdateCallback(consumer);
+    }
+
+    @Override
+    public void update() {
+        if (isActualTransactionActive()) {
+            registerSynchronization(new TransactionSynchronization() {
+                @Override
+                public void afterCommit() {
+                    watcher.update();
+                }
+            });
+        } else {
+            watcher.update();
+        }
+    }
+}

src/main/java/org/casbin/spring/boot/autoconfigure/properties/CasbinProperties.java

@@ -72,6 +72,11 @@ public class CasbinProperties {
      */
     private CasbinWatcherLettuceRedisType watcherLettuceRedisType = CasbinWatcherLettuceRedisType.NONE;
 
+    /**
+     * Use {@link org.casbin.spring.boot.autoconfigure.TxWatcher} proxy, update after the transaction is committed
+     */
+    private boolean watcherTxSupport = false;
+
     public String getModelContext() {
         String text = FileUtils.getFileAsText(model);
         if (text == null) {
@@ -193,4 +198,12 @@ public CasbinWatcherLettuceRedisType getWatcherLettuceRedisType() {
     public void setWatcherLettuceRedisType(CasbinWatcherLettuceRedisType watcherLettuceRedisType) {
         this.watcherLettuceRedisType = watcherLettuceRedisType;
     }
-}
+
+    public boolean isWatcherTxSupport() {
+        return watcherTxSupport;
+    }
+
+    public void setWatcherTxSupport(boolean watcherTxSupport) {
+        this.watcherTxSupport = watcherTxSupport;
+    }
+}