[ECO-5246] fix: Realtime Client Reconnection Logic

[ttypic]

Resolves #1074

Previously, we cleared all channels on the close event, causing all previously acquired channels to become orphaned. We have now removed this logic and fixed the reconnection behavior to align with the spec

Summary by CodeRabbit

Summary by CodeRabbit

• Refactor

  • Modified channel management to prevent automatic clearing of channels upon connection closure, allowing for persistent channel states.

• New Features

  • Introduced a mechanism to reinitialize channels, resetting their states and error conditions during reconnection for smoother recovery.

• Tests

  • Added tests to validate that channels properly reset when reconnecting from closed or closing states.

[coderabbitai]

Walkthrough

The changes involve the removal of a listener in the AblyRealtime class that previously cleared all channels upon disconnection. A new synchronized method, setReinitialized(), has been added to the ChannelBase class to reset the channel's state. Additionally, the ConnectionManager class has been updated with new methods to manage connection states more effectively. New tests have been introduced to ensure channels are properly reinitialized when a client reconnects from closed or closing states.

Changes

File(s)	Change Summary
lib/.../ChannelBase.java lib/.../ConnectionManager.java	Added channel state reinitialization support: introduced setReinitialized() in ChannelBase and enactForChannel(), cleanMsgSerialAndErrorReason(), and hasConnectBeenInvokeOnClosedOrFailedState() in ConnectionManager to update channel states upon reconnection events.
lib/.../AblyRealtime.java	Removed the listener that automatically cleared channels when the connection state changed to closed.
lib/.../RealtimeChannelTest.java	Added tests validating that channels are reinitialized (state set to initialized and error cleared) when a client reconnects from closed or closing states.

Sequence Diagram(s)

sequenceDiagram
    participant Client
    participant ConnManager as ConnectionManager
    participant Channel as ChannelBase

    Client->>ConnManager: Initiate reconnection
    ConnManager->>Channel: Check previous connection state
    alt State was closing
        ConnManager->>Channel: setConnectionClosed(REASON_CLOSED)
    end
    alt State was closed/failed
        ConnManager->>Channel: setReinitialized()
    end
    Channel-->>ConnManager: Channel reset confirmed
    ConnManager-->>Client: Connection reestablished

Loading

Assessment against linked issues

Objective	Addressed	Explanation
Transition channels to INITIALIZED state when CLOSED or FAILED (#[1074], #[ECO-5246])	✅
Clear error reasons and reset msgSerial to 0 upon reconnection (#[1074], #[ECO-5246])	✅

Possibly related PRs

• [ECO-5033] fix: race condition when callingAblyRealtime#connect() on terminated state #1042: The changes in the main PR, which involve the removal of a listener that clears channels upon connection closure, are related to the modifications in this PR that enhance connection state management and introduce new methods for handling channel states during reconnections.
• [ECO-5117] Fix channel ATTACH/DETACH state checks #1046: The changes in the main PR, which involve the removal of a listener that clears channels upon connection closure, are related to the modifications in this PR that enhance channel state management, particularly regarding the handling of channel states during connection transitions.

Suggested reviewers

• sacOO7

Poem

I'm a rabbit who hops through lines of code,
Celebrating changes on this winding road.
Channels reinitialized with a joyful leap,
Listeners removed—no more cleanup to keep!
Hop along with me on this digital spree,
Where every reconnected channel sings with glee.
🐇✨

---

📜 Recent review details

Configuration used: CodeRabbit UI
Review profile: CHILL
Plan: Pro (Legacy)

📥 Commits

Reviewing files that changed from the base of the PR and between 841c69e and ef11880.

📒 Files selected for processing (4)

• lib/src/main/java/io/ably/lib/realtime/AblyRealtime.java (0 hunks)
• lib/src/main/java/io/ably/lib/realtime/ChannelBase.java (1 hunks)
• lib/src/main/java/io/ably/lib/transport/ConnectionManager.java (2 hunks)
• lib/src/test/java/io/ably/lib/test/realtime/RealtimeChannelTest.java (2 hunks)

💤 Files with no reviewable changes (1)

• lib/src/main/java/io/ably/lib/realtime/AblyRealtime.java

🚧 Files skipped from review as they are similar to previous changes (1)

• lib/src/main/java/io/ably/lib/realtime/ChannelBase.java

⏰ Context from checks skipped due to timeout of 90000ms (8)

• GitHub Check: check-rest-okhttp
• GitHub Check: check (29)
• GitHub Check: check (24)
• GitHub Check: check-realtime-okhttp
• GitHub Check: check (21)
• GitHub Check: check-realtime
• GitHub Check: check (19)
• GitHub Check: check-rest

🔇 Additional comments (6)

lib/src/main/java/io/ably/lib/transport/ConnectionManager.java (4)

235-238: Implementation looks good for handling connection state transition.

This code properly implements RTN11d by cleaning the message serial and error reason when reconnecting from a closed or failed state. The conditional check ensures this only happens when appropriate.

---

243-254: Well-implemented channel state transition handling based on connection state.

Good implementation of specs RTN11b and RTN11d:

• For channels during a transition from closing state, properly sets the channel as closed
• For channels during a transition from closed/failed states, reinitializes them appropriately

The code is well-commented with the relevant spec references.

---

1580-1586: Correct implementation of msgSerial reset and reason clearing.

This method properly implements the RTN11d spec by resetting the message serial counter to 0 and clearing any connection error reasons, which are important steps for handling reconnection correctly.

---

1588-1592: Good helper method to check previous connection state.

This helper method correctly identifies if the previous connection state was failed, closed, or closing, which is needed to determine when channel reinitialization should occur.

lib/src/test/java/io/ably/lib/test/realtime/RealtimeChannelTest.java (2)

2466-2508: Good test for channel reinitialization from closed state.

This test thoroughly verifies the RTN11d specification by ensuring that:

1. A channel in a closed state is properly reinitialized when reconnecting
2. The channel error reason is cleared
3. The connection error reason is cleared
4. The message serial is reset to 0

The test creates a realistic scenario by first establishing a connection, attaching a channel, publishing a message to increment msgSerial, then closing and reconnecting.

---

2510-2559: Comprehensive test for channel reinitialization from closing state.

This test thoroughly verifies the RTN11b specification by ensuring that:

1. A channel in a closing state is properly reinitialized when reconnecting
2. The channel error reason is cleared
3. The message serial is reset to 0
4. The channel transitions through the expected states

Good use of state change tracking to verify the exact sequence of state transitions, which adds confidence that the implementation behaves correctly.

---

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[sacOO7]

Not sure why tests are failing

[sacOO7]

LGTM