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CB-303 part 1: idle_ttl session reaper (injectable clock + SessionReaper)

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This commit is contained in:
Dai Ha
2026-07-17 09:52:40 +02:00
parent 64e70efdf1
commit 8d51066ddd
7 changed files with 322 additions and 11 deletions
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bridged/src/main/java/dev/ltms/bridged/Bridged.java
+11
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@@ -20,6 +20,7 @@ import dev.ltms.bridged.msg.Rendezvous;
import dev.ltms.bridged.rest.BridgedApp;
import dev.ltms.bridged.session.GitWorktrees;
import dev.ltms.bridged.session.SessionManager;
import dev.ltms.bridged.session.SessionReaper;
import dev.ltms.bridged.worker.WorkerService;
import io.javalin.Javalin;
import org.slf4j.Logger;
@@ -66,6 +67,16 @@ public final class Bridged {
// CB-301-ext: worktree provisioning seam, optionally rooted at a configured directory.
SessionManager sessions = new SessionManager(workers, new GitWorktrees(cfg.worktreeRoot()));
// CB-303 part 1: idle-ttl reaper — only when configured, defaults to disabled.
SessionReaper reaper = null;
if (cfg.lifecycle() != null
&& cfg.lifecycle().idleTtlSeconds() != null
&& cfg.lifecycle().idleTtlSeconds() > 0) {
reaper = new SessionReaper(sessions, cfg.lifecycle().idleTtlSeconds());
reaper.start();
Runtime.getRuntime().addShutdownHook(new Thread(reaper::stop));
}
// Status-gated injector (CB-103): the single writer into workers, fed by a poller.
// The blocking message endpoint (CB-104) is the producer; the poller is inert until then.
// CB-106: a confirmed turn completion resolves a blocked send whose worker never replied.
bridged/src/main/java/dev/ltms/bridged/config/BridgedConfig.java
+20 -2
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@@ -27,6 +27,7 @@ import java.util.Set;
* @param guard subscription-boundary allowlist
* @param worktreeRoot nullable root directory for provisioned worktrees; defaults to a sibling
* of the repo root
* @param lifecycle session lifecycle limits ({@code null} = all disabled)
*/
@JsonIgnoreProperties(ignoreUnknown = true)
public record BridgedConfig(
@@ -36,7 +37,8 @@ public record BridgedConfig(
Map<String, Worker> workers,
String defaultWorker,
Guard guard,
String worktreeRoot) {
String worktreeRoot,
Lifecycle lifecycle) {
@JsonIgnoreProperties(ignoreUnknown = true)
public record Bind(String host, int port) {
@@ -144,6 +146,21 @@ public record BridgedConfig(
}
}
/**
* Session lifecycle limits. All knobs are opt-in: {@code null} or {@code 0} disables the
* feature so existing configs keep the previous behaviour.
*
* @param idleTtlSeconds max seconds a {@code READY}/{@code DONE} session may sit idle
* before it is reaped ({@code null} → disabled)
* @param contextCap max delegated turns a session serves before force-release
* ({@code null} → disabled)
* @param drainTimeoutSeconds seconds to wait for {@code BUSY} sessions to finish before
* forced teardown on shutdown (default 5 when unset)
*/
@JsonIgnoreProperties(ignoreUnknown = true)
public record Lifecycle(Integer idleTtlSeconds, Integer contextCap, Integer drainTimeoutSeconds) {
}
/**
* Subscription boundary. Only these hosts may back a worker's
* {@code ANTHROPIC_BASE_URL}; the primary must carry none.
@@ -211,6 +228,7 @@ public record BridgedConfig(
public BridgedConfig withDefaults() {
Bind b = bind != null ? bind : new Bind(null, 0);
Guard g = guard != null ? guard : new Guard(List.of());
return new BridgedConfig(b, herdrSocket, worker, workers, defaultWorker, g, worktreeRoot);
Lifecycle l = lifecycle != null ? lifecycle : new Lifecycle(null, null, null);
return new BridgedConfig(b, herdrSocket, worker, workers, defaultWorker, g, worktreeRoot, l);
}
}
bridged/src/main/java/dev/ltms/bridged/session/SessionManager.java
+83 -4
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@@ -11,7 +11,9 @@ import java.security.SecureRandom;
import java.util.List;
import java.util.Optional;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;
import java.util.function.LongSupplier;
/**
* Authoritative in-daemon registry of the worker sessions this {@code bridged} process spawned.
@@ -37,16 +39,24 @@ public final class SessionManager implements TurnListener {
private final WorkerPresence presence;
private final SecureRandom nonceRandom = new SecureRandom();
private final AtomicLong nonceSeq = new AtomicLong();
private final LongSupplier nowNanos;
/** Backward-compatible constructor: shared-tree sessions, production git seam. */
public SessionManager(WorkerService workerService) {
this(workerService, new GitWorktrees());
this(workerService, new GitWorktrees(), System::nanoTime);
}
/** Backward-compatible constructor with an injectable worktree seam. */
public SessionManager(WorkerService workerService, Worktrees worktrees) {
this(workerService, worktrees, System::nanoTime);
}
/** Test constructor with an injectable clock. */
public SessionManager(WorkerService workerService, Worktrees worktrees, LongSupplier nowNanos) {
this.workerService = workerService;
this.worktrees = worktrees;
this.presence = new PresenceBridge(this);
this.nowNanos = nowNanos;
}
/**
@@ -80,13 +90,16 @@ public final class SessionManager implements TurnListener {
Agent worker = workerService.spawn(profile, requestedCwd, callerCwd);
String resolvedProfile = (profile == null || profile.isBlank())
? workerService.defaultProfile() : profile;
long now = nowNanos.getAsLong();
WorkerSession session = new WorkerSession(
worker.paneId(),
worker.terminalId(),
resolvedProfile,
resolveCwd(requestedCwd, profile, callerCwd),
ownerTerminal,
System.nanoTime(),
now,
now,
0,
WorkerSession.State.SPAWNING,
null,
null);
@@ -133,13 +146,16 @@ public final class SessionManager implements TurnListener {
}
throw e;
}
long now = nowNanos.getAsLong();
WorkerSession session = new WorkerSession(
worker.paneId(),
worker.terminalId(),
resolvedProfile,
resolveCwd(path, profile, callerCwd),
ownerTerminal,
System.nanoTime(),
now,
now,
0,
WorkerSession.State.SPAWNING,
path,
branch);
@@ -220,6 +236,68 @@ public final class SessionManager implements TurnListener {
}
}
/**
* Best-effort reap of sessions that have been idle longer than {@code idleTtlNanos}. Only
* {@code READY} and {@code DONE} sessions are eligible — never a {@code SPAWNING} or
* {@code BUSY} worker. Returns the number of sessions released.
*/
int reapIdle(long idleTtlNanos) {
long now = nowNanos.getAsLong();
int reaped = 0;
for (WorkerSession s : roster()) {
if (s.state() != WorkerSession.State.READY && s.state() != WorkerSession.State.DONE) {
continue;
}
if (now - s.lastActivityAtNanos() > idleTtlNanos) {
release(s.paneId());
reaped++;
}
}
return reaped;
}
/**
* Gracefully drain all registered sessions. For each session that is {@code BUSY}, poll up to
* {@code timeoutNanos} for it to leave {@code BUSY}, then release it regardless. Non-busy
* sessions are released immediately. A failure releasing one session is logged and does not
* abort the rest.
*/
void drainAll(long timeoutNanos) {
long deadline = nowNanos.getAsLong() + timeoutNanos;
long pollNanos = TimeUnit.MILLISECONDS.toNanos(50);
for (WorkerSession s : roster()) {
try {
if (s.state() == WorkerSession.State.BUSY) {
while (nowNanos.getAsLong() < deadline) {
WorkerSession current = registry.get(s.paneId());
if (current == null || current.state() != WorkerSession.State.BUSY) {
break;
}
try {
long remaining = deadline - nowNanos.getAsLong();
Thread.sleep(Math.min(TimeUnit.NANOSECONDS.toMillis(remaining), 50));
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
break;
}
}
}
release(s.paneId());
} catch (RuntimeException e) {
log.warn("drain failed for pane={}; continuing with remaining sessions", s.paneId(), e);
}
}
}
/**
* Close this manager by draining all sessions. The timeout comes from configuration when set,
* otherwise a sensible default.
*/
public void close(Integer drainTimeoutSeconds) {
int seconds = (drainTimeoutSeconds != null && drainTimeoutSeconds > 0) ? drainTimeoutSeconds : 5;
drainAll(TimeUnit.SECONDS.toNanos(seconds));
}
/** Number of sessions currently registered. */
public int size() {
return registry.size();
@@ -236,7 +314,8 @@ public final class SessionManager implements TurnListener {
WorkerSession.State to) {
WorkerSession current = findByTerminal(terminalId);
if (current == null || current.state() != from) return;
if (replace(current, current.withState(to))) {
long now = nowNanos.getAsLong();
if (replace(current, current.withState(to).withActivity(now))) {
log.debug("session transitioned terminal={} pane={} {} -> {}",
terminalId, current.paneId(), from, to);
}
bridged/src/main/java/dev/ltms/bridged/session/SessionReaper.java
+70
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@@ -0,0 +1,70 @@
package dev.ltms.bridged.session;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.concurrent.TimeUnit;
/**
* Periodic virtual-thread reaper that tears down {@code READY}/{@code DONE} sessions which have
* exceeded their idle TTL. Modeled on {@link dev.ltms.bridged.inject.StatusPoller}: a single
* virtual-thread loop, idempotent start/stop, and no {@code ScheduledExecutorService}.
*/
public final class SessionReaper {
private static final Logger log = LoggerFactory.getLogger(SessionReaper.class);
private static final long DEFAULT_INTERVAL_MILLIS = 5000;
private final SessionManager sessions;
private final long idleTtlNanos;
private final long intervalMillis;
private volatile boolean running;
private Thread thread;
/** Construct a reaper with the default 5-second polling interval. */
public SessionReaper(SessionManager sessions, long idleTtlSeconds) {
this(sessions, idleTtlSeconds, DEFAULT_INTERVAL_MILLIS);
}
/** Construct a reaper with an explicit polling interval (useful for tests). */
public SessionReaper(SessionManager sessions, long idleTtlSeconds, long intervalMillis) {
this.sessions = sessions;
this.idleTtlNanos = TimeUnit.SECONDS.toNanos(idleTtlSeconds);
this.intervalMillis = intervalMillis;
}
/** Start the reaper loop on a virtual thread. Idempotent. */
public synchronized void start() {
if (running) return;
running = true;
thread = Thread.ofVirtual().name("session-reaper").start(this::loop);
log.info("session reaper started (idle ttl {}s, interval {}ms)",
TimeUnit.NANOSECONDS.toSeconds(idleTtlNanos), intervalMillis);
}
private void loop() {
while (running) {
try {
sessions.reapIdle(idleTtlNanos);
} catch (RuntimeException e) {
log.warn("session reaper iteration failed; continuing", e);
}
sleep();
}
}
private void sleep() {
try {
Thread.sleep(intervalMillis);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
running = false;
}
}
/** Stop the reaper loop. Idempotent. */
public synchronized void stop() {
running = false;
if (thread != null) thread.interrupt();
}
}
bridged/src/main/java/dev/ltms/bridged/session/WorkerSession.java
+20 -4
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@@ -10,8 +10,10 @@ package dev.ltms.bridged.session;
* @param profile the worker profile name that spawned this session
* @param cwd the resolved working directory the worker started in
* @param ownerTerminal the caller that requested this worker ({@code null} = daemon/anon)
* @param spawnedAtNanos {@link System#nanoTime()} when the session was registered
* @param state current lifecycle state in the one-shot FSM
* @param spawnedAtNanos {@link System#nanoTime()} when the session was registered
* @param lastActivityAtNanos {@link System#nanoTime()} of the most recent lifecycle event
* @param turnCount number of delegated turns that have been delivered to this session
* @param state current lifecycle state in the one-shot FSM
*/
public record WorkerSession(
String paneId,
@@ -20,6 +22,8 @@ public record WorkerSession(
String cwd,
String ownerTerminal,
long spawnedAtNanos,
long lastActivityAtNanos,
int turnCount,
State state,
String worktree,
String branch) {
@@ -36,7 +40,19 @@ public record WorkerSession(
/** Return a copy of this session in {@code state}. */
public WorkerSession withState(State state) {
return new WorkerSession(paneId, terminalId, profile, cwd, ownerTerminal, spawnedAtNanos, state,
worktree, branch);
return new WorkerSession(paneId, terminalId, profile, cwd, ownerTerminal, spawnedAtNanos,
lastActivityAtNanos, turnCount, state, worktree, branch);
}
/** Return a copy with {@code lastActivityAtNanos} updated to {@code nowNanos}. */
public WorkerSession withActivity(long nowNanos) {
return new WorkerSession(paneId, terminalId, profile, cwd, ownerTerminal, spawnedAtNanos,
nowNanos, turnCount, state, worktree, branch);
}
/** Return a copy with the turn count incremented and activity timestamped at {@code nowNanos}. */
public WorkerSession bumpTurn(long nowNanos) {
return new WorkerSession(paneId, terminalId, profile, cwd, ownerTerminal, spawnedAtNanos,
nowNanos, turnCount + 1, state, worktree, branch);
}
}