From abd29143d805fa16c65489d5b1d79428943d0187 Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@tavianator.com>
Date: Mon, 26 Jun 2023 11:47:41 -0400
Subject: ioq: New ioq_cancel() function

---
 src/bftw.c |  4 ++++
 src/ioq.c  | 27 ++++++++++++++++++++-------
 src/ioq.h  |  5 +++++
 3 files changed, 29 insertions(+), 7 deletions(-)

diff --git a/src/bftw.c b/src/bftw.c
index 69e41a2..2bdf12d 100644
--- a/src/bftw.c
+++ b/src/bftw.c
@@ -1147,6 +1147,10 @@ static int bftw_gc(struct bftw_state *state, enum bftw_gc_flags flags) {
 static int bftw_state_destroy(struct bftw_state *state) {
 	dstrfree(state->path);
 
+	if (state->ioq) {
+		ioq_cancel(state->ioq);
+	}
+
 	SLIST_EXTEND(&state->files, &state->batch);
 	do {
 		bftw_gc(state, BFTW_VISIT_NONE);
diff --git a/src/ioq.c b/src/ioq.c
index 617bd5f..457ead7 100644
--- a/src/ioq.c
+++ b/src/ioq.c
@@ -264,6 +264,8 @@ struct ioq {
 	size_t depth;
 	/** The current size of the queue. */
 	size_t size;
+	/** Cancellation flag. */
+	atomic bool cancel;
 
 	/** ioq_cmd command arena. */
 	struct arena cmds;
@@ -289,17 +291,22 @@ static void *ioq_work(void *ptr) {
 			break;
 		}
 
+		bool cancel = load(&ioq->cancel, relaxed);
+
 		struct ioq_req req = cmd->req;
 		sanitize_uninit(cmd);
 
 		struct ioq_res *res = &cmd->res;
 		res->ptr = req.ptr;
 		res->dir = req.dir;
-		res->error = 0;
-		if (bfs_opendir(req.dir, req.dfd, req.path) == 0) {
-			bfs_polldir(res->dir);
-		} else {
+
+		if (cancel) {
+			res->error = EINTR;
+		} else if (bfs_opendir(req.dir, req.dfd, req.path) != 0) {
 			res->error = errno;
+		} else {
+			res->error = 0;
+			bfs_polldir(res->dir);
 		}
 
 		ioqq_push(ioq->ready, cmd);
@@ -394,14 +401,20 @@ void ioq_free(struct ioq *ioq, struct ioq_res *res) {
 	arena_free(&ioq->cmds, (union ioq_cmd *)res);
 }
 
+void ioq_cancel(struct ioq *ioq) {
+	if (!exchange(&ioq->cancel, true, relaxed)) {
+		for (size_t i = 0; i < ioq->nthreads; ++i) {
+			ioqq_push(ioq->pending, &IOQ_STOP);
+		}
+	}
+}
+
 void ioq_destroy(struct ioq *ioq) {
 	if (!ioq) {
 		return;
 	}
 
-	for (size_t i = 0; i < ioq->nthreads; ++i) {
-		ioqq_push(ioq->pending, &IOQ_STOP);
-	}
+	ioq_cancel(ioq);
 
 	for (size_t i = 0; i < ioq->nthreads; ++i) {
 		if (pthread_join(ioq->threads[i], NULL) != 0) {
diff --git a/src/ioq.h b/src/ioq.h
index 50e02b1..064e2e2 100644
--- a/src/ioq.h
+++ b/src/ioq.h
@@ -88,6 +88,11 @@ struct ioq_res *ioq_trypop(struct ioq *ioq);
  */
 void ioq_free(struct ioq *ioq, struct ioq_res *res);
 
+/**
+ * Cancel any pending I/O operations.
+ */
+void ioq_cancel(struct ioq *ioq);
+
 /**
  * Stop and destroy an I/O queue.
  */
-- 
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