IGNITE-27651 Clean up direct tx on client disconnect

[ptupitsyn]

Store remote enlistments in client resource registry and clean up on disconnect.

[Copilot]

Pull request overview

Adds server-side tracking/cleanup for direct-mapped (lightweight) client transactions so that partitions enlisted on a node can be cleaned up when a client disconnects, and documents the direct-tx coordinator flow.

Changes:

• Expose RemotelyTriggeredResourceRegistry via TxManager and wire it in TxManagerImpl.
• Track direct-tx remote enlistments per client connection and attempt cleanup on disconnect; refactor discard cleanup into ClientTxPartitionEnlistmentCleaner.
• Add/enable integration tests around tx cleanup and JDBC transaction failover behavior.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
modules/transactions/src/main/java/org/apache/ignite/internal/tx/impl/TxManagerImpl.java	Stores and exposes RemotelyTriggeredResourceRegistry via new resourceRegistry() API.
modules/transactions/src/main/java/org/apache/ignite/internal/tx/TxManager.java	Adds resourceRegistry() accessor to support cross-module cleanup registration.
modules/client-handler/src/main/java/org/apache/ignite/client/handler/ClientResourceRegistry.java	Tracks per-connection tx cleaners and triggers cleanup on disconnect.
modules/client-handler/src/main/java/org/apache/ignite/client/handler/requests/table/ClientTableCommon.java	Registers per-tx cleanup hooks when processing direct-mapped requests.
modules/client-handler/src/main/java/org/apache/ignite/client/handler/requests/tx/ClientTxPartitionEnlistmentCleaner.java	New helper to collect enlistments and invoke discardLocalWriteIntents.
modules/client-handler/src/main/java/org/apache/ignite/client/handler/requests/tx/ClientTransactionDiscardRequest.java	Refactors discard request handling to reuse the new cleaner helper.
modules/runner/src/integrationTest/java/org/apache/ignite/internal/runner/app/client/ItThinClientTransactionCleanupTest.java	New IT covering “disconnect releases locks” scenario for direct tx.
modules/jdbc/src/integrationTest/java/org/apache/ignite/jdbc/ItJdbcConnectionFailoverTest.java	Re-enables a previously disabled failover test.
modules/client/src/test/java/org/apache/ignite/client/fakes/FakeTxManager.java	Implements new TxManager.resourceRegistry() method (currently returns null).
modules/client/src/main/java/org/apache/ignite/internal/client/tx/DEVNOTES.md	New developer notes describing the direct transaction coordinator protocol/lifecycle.

Comments suppressed due to low confidence (1)

modules/client-handler/src/main/java/org/apache/ignite/client/handler/ClientResourceRegistry.java:180

• Catching Throwable during resource cleanup will also swallow serious Errors (e.g., OutOfMemoryError, StackOverflowError) and continue execution, which can leave the JVM in an inconsistent state and makes diagnosing such failures harder. It's safer to catch Exception here (and let Error propagate), while still collecting/suppressing regular cleanup failures.

        for (ClientResource r : res.values()) {
            try {
                r.release();
            } catch (Throwable e) {
                if (ex == null) {
                    ex = new IgniteInternalException(e);
                } else {
                    ex.addSuppressed(e);
                }
            }

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[Copilot]

Pull request overview

This PR aims to ensure server-side cleanup of direct-mapped (lightweight) client transactions when a thin client disconnects, by tracking remote partition enlistments per client connection and triggering write-intent/lock cleanup.

Changes:

• Add per-connection tracking of direct-tx partition enlistments in ClientResourceRegistry, and run cleanup on registry close (client disconnect).
• Refactor discard cleanup logic into a dedicated helper (ClientTxPartitionEnlistmentCleaner) and integrate enlistment tracking into direct-tx request processing.
• Expose RemotelyTriggeredResourceRegistry via TxManager and add an integration test for lock release on disconnect.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
modules/transactions/src/main/java/org/apache/ignite/internal/tx/impl/TxManagerImpl.java	Stores injected resource registry and exposes it via new TxManager.resourceRegistry().
modules/transactions/src/main/java/org/apache/ignite/internal/tx/TxManager.java	Adds resourceRegistry() accessor to support registering tx-finish callbacks.
modules/client-handler/src/main/java/org/apache/ignite/client/handler/ClientResourceRegistry.java	Tracks per-tx cleaners and triggers cleanup on registry close (disconnect).
modules/client-handler/src/main/java/org/apache/ignite/client/handler/requests/table/ClientTableCommon.java	Records direct-tx enlistments for disconnect cleanup and registers tx-finish untracking.
modules/client-handler/src/main/java/org/apache/ignite/client/handler/requests/tx/ClientTxPartitionEnlistmentCleaner.java	New helper that groups enlisted partitions and calls discardLocalWriteIntents.
modules/client-handler/src/main/java/org/apache/ignite/client/handler/requests/tx/ClientTransactionDiscardRequest.java	Uses the new cleaner helper instead of duplicating enlistment grouping logic.
modules/runner/src/integrationTest/java/org/apache/ignite/internal/runner/app/client/ItThinClientTransactionCleanupTest.java	New integration test verifying locks are released after client disconnect with direct enlistments.
modules/jdbc/src/integrationTest/java/org/apache/ignite/jdbc/ItJdbcConnectionFailoverTest.java	Re-enables a previously disabled transaction failover test.
modules/client/src/test/java/org/apache/ignite/client/fakes/FakeTxManager.java	Updates test fake for the new TxManager.resourceRegistry() method.
modules/client/src/main/java/org/apache/ignite/internal/client/tx/DEVNOTES.md	Adds developer documentation describing the direct transaction coordinator flow.

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