Merge pull request #108 from denyskonakhevych/LB-2097

LB-2097: Lock acquisition concurrency issue
liquibase · May 24, 2022 · 8843c75 · 8843c75
2 parents f722c71 + 1675d8e
commit 8843c75
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Showing 2 changed files with 29 additions and 8 deletions.
diff --git a/src/main/java/liquibase/ext/cassandra/lockservice/LockServiceCassandra.java b/src/main/java/liquibase/ext/cassandra/lockservice/LockServiceCassandra.java
@@ -17,7 +17,10 @@
 import liquibase.statement.core.LockDatabaseChangeLogStatement;
 import liquibase.statement.core.RawSqlStatement;
 import liquibase.statement.core.UnlockDatabaseChangeLogStatement;
+import liquibase.util.NetUtil;
 
+import java.net.SocketException;
+import java.net.UnknownHostException;
 import java.sql.SQLException;
 import java.sql.Statement;
 
@@ -51,17 +54,16 @@ public boolean acquireLock() throws LockException {
             super.init();
 
 
-            boolean locked = executor.queryForInt(
-                    new RawSqlStatement("SELECT COUNT(*) FROM " + getChangeLogLockTableName() + " where " +
-                            "locked = TRUE ALLOW FILTERING")
-            ) > 0;
-
-            if (locked) {
+            if (isLocked(executor)) {
                 return false;
             } else {
 
                 executor.comment("Lock Database");
                 int rowsUpdated = executor.update(new LockDatabaseChangeLogStatement());
+                if (rowsUpdated == -1 && !isLockedByCurrentInstance(executor)) {
+                    // another node was faster
+                    return false;
+                }
                 if ((rowsUpdated == -1) && (database instanceof MSSQLDatabase)) {
 
                     Scope.getCurrentScope().getLog(this.getClass()).info("Database did not return a proper row count (Might have NOCOUNT enabled)");
@@ -178,8 +180,27 @@ public boolean isDatabaseChangeLogLockTableInitialized(final boolean tableJustCr
         return isDatabaseChangeLogLockTableInitialized;
     }
 
+    private boolean isLocked(Executor executor) throws DatabaseException {
+        return executor.queryForInt(
+                new RawSqlStatement("SELECT COUNT(*) FROM " + database.getDefaultCatalogName() + "." + getChangeLogLockTableName() + " where " +
+                        "locked = TRUE ALLOW FILTERING")
+        ) > 0;
+    }
+
+    private boolean isLockedByCurrentInstance(Executor executor) throws DatabaseException {
+        try {
+            final String lockedBy = NetUtil.getLocalHostName() + " (" + NetUtil.getLocalHostAddress() + ")";
+            return executor.queryForInt(
+                    new RawSqlStatement("SELECT COUNT(*) FROM " + database.getDefaultCatalogName() + "." + getChangeLogLockTableName() + " where " +
+                            "LOCKED = TRUE AND LOCKEDBY = '" + lockedBy + "' ALLOW FILTERING")
+            ) > 0;
+        } catch (SocketException | UnknownHostException e) {
+            throw new UnexpectedLiquibaseException(e);
+        }
+    }
+
     private String getChangeLogLockTableName() {
-        if(database.getLiquibaseCatalogName() != null) {
+        if (database.getLiquibaseCatalogName() != null) {
             return database.getLiquibaseCatalogName() + "." + database.getDatabaseChangeLogLockTableName();
         } else {
             return database.getDatabaseChangeLogLockTableName();

diff --git a/...in/java/liquibase/ext/cassandra/sqlgenerator/LockDatabaseChangeLogGeneratorCassandra.java b/...in/java/liquibase/ext/cassandra/sqlgenerator/LockDatabaseChangeLogGeneratorCassandra.java
@@ -25,7 +25,7 @@ public boolean supports(LockDatabaseChangeLogStatement statement, Database datab
     public Sql[] generateSql(LockDatabaseChangeLogStatement statement, Database database, SqlGeneratorChain sqlGeneratorChain) {
         RawSqlStatement updateStatement = new RawSqlStatement("UPDATE " +
                 database.escapeTableName(database.getLiquibaseCatalogName(), database.getLiquibaseSchemaName(), database.getDatabaseChangeLogLockTableName()) +
-                " SET LOCKED = TRUE, LOCKEDBY = '" + hostname + " (" + hostaddress + ")" + "', LOCKGRANTED = " + System.currentTimeMillis() + " WHERE ID = 1");
+                " SET LOCKED = TRUE, LOCKEDBY = '" + hostname + " (" + hostaddress + ")" + "', LOCKGRANTED = " + System.currentTimeMillis() + " WHERE ID = 1 IF LOCKED = FALSE");
         return SqlGeneratorFactory.getInstance().generateSql(updateStatement, database);
     }