Support cancellation in push operation

This commit adds cancellation for the push operation. This work consists of:

1) Support cancellation during push operation
    - During object counting phase
    - During network transfer phase
        - Propagate GIT_EUSER error code out to caller
2) Improve cancellation support during fetch
    - Handle cancellation request during network transfer phase
    - Clear error string when cancelled during indexing
3) Fix error handling in git_smart__download_pack

Cancellation during push is still only handled in the pack building and
network transfer stages of push (and not during packbuilding).

include/git2/pack.h

@@ -158,7 +158,7 @@ GIT_EXTERN(uint32_t) git_packbuilder_object_count(git_packbuilder *pb);
 GIT_EXTERN(uint32_t) git_packbuilder_written(git_packbuilder *pb);
 
 /** Packbuilder progress notification function */
-typedef void (*git_packbuilder_progress)(
+typedef int (*git_packbuilder_progress)(
 	int stage,
 	unsigned int current,
 	unsigned int total,

include/git2/push.h

@@ -40,7 +40,7 @@ typedef struct {
 #define GIT_PUSH_OPTIONS_INIT { GIT_PUSH_OPTIONS_VERSION }
 
 /** Push network progress notification function */
-typedef void (*git_push_transfer_progress)(
+typedef int (*git_push_transfer_progress)(
 	unsigned int current,
 	unsigned int total,
 	size_t bytes,

src/indexer.c

@@ -556,6 +556,7 @@ int git_indexer_stream_add(git_indexer_stream *idx, const void *data, size_t siz
 		stats->received_objects++;
 
 		if (do_progress_callback(idx, stats) != 0) {
+			giterr_clear();
 			error = GIT_EUSER;
 			goto on_error;
 		}

src/pack-objects.c

@@ -216,15 +216,19 @@ int git_packbuilder_insert(git_packbuilder *pb, const git_oid *oid,
 	assert(ret != 0);
 	kh_value(pb->object_ix, pos) = po;
 
+	pb->done = false;
+
 	if (pb->progress_cb) {
 		double current_time = git__timer();
 		if ((current_time - pb->last_progress_report_time) >= MIN_PROGRESS_UPDATE_INTERVAL) {
 			pb->last_progress_report_time = current_time;
-			pb->progress_cb(GIT_PACKBUILDER_ADDING_OBJECTS, pb->nr_objects, 0, pb->progress_cb_payload);
+			if (pb->progress_cb(GIT_PACKBUILDER_ADDING_OBJECTS, pb->nr_objects, 0, pb->progress_cb_payload)) {
+				giterr_clear();
+				return GIT_EUSER;
+			}
 		}
 	}
 
-	pb->done = false;
 	return 0;
 }
 
@@ -591,49 +595,50 @@ static int write_pack(git_packbuilder *pb,
 	enum write_one_status status;
 	struct git_pack_header ph;
 	unsigned int i = 0;
+	int error = 0;
 
 	write_order = compute_write_order(pb);
-	if (write_order == NULL)
-		goto on_error;
+	if (write_order == NULL) {
+		error = -1;
+		goto done;
+	}
 
 	/* Write pack header */
 	ph.hdr_signature = htonl(PACK_SIGNATURE);
 	ph.hdr_version = htonl(PACK_VERSION);
 	ph.hdr_entries = htonl(pb->nr_objects);
 
-	if (cb(&ph, sizeof(ph), data) < 0)
-		goto on_error;
+	if ((error = cb(&ph, sizeof(ph), data)) < 0)
+		goto done;
 
-	if (git_hash_update(&pb->ctx, &ph, sizeof(ph)) < 0)
-		goto on_error;
+	if ((error = git_hash_update(&pb->ctx, &ph, sizeof(ph))) < 0)
+		goto done;
 
 	pb->nr_remaining = pb->nr_objects;
 	do {
 		pb->nr_written = 0;
 		for ( ; i < pb->nr_objects; ++i) {
 			po = write_order[i];
-			if (write_one(&buf, pb, po, &status) < 0)
-				goto on_error;
-			if (cb(buf.ptr, buf.size, data) < 0)
-				goto on_error;
+			if ((error = write_one(&buf, pb, po, &status)) < 0)
+				goto done;
+			if ((error = cb(buf.ptr, buf.size, data)) < 0)
+				goto done;
 			git_buf_clear(&buf);
 		}
 
 		pb->nr_remaining -= pb->nr_written;
 	} while (pb->nr_remaining && i < pb->nr_objects);
 
-	git__free(write_order);
-	git_buf_free(&buf);
 
-	if (git_hash_final(&pb->pack_oid, &pb->ctx) < 0)
-		goto on_error;
+	if ((error = git_hash_final(&pb->pack_oid, &pb->ctx)) < 0)
+		goto done;
 
-	return cb(pb->pack_oid.id, GIT_OID_RAWSZ, data);
+	error = cb(pb->pack_oid.id, GIT_OID_RAWSZ, data);
 
-on_error:
+done:
 	git__free(write_order);
 	git_buf_free(&buf);
-	return -1;
+	return error;
 }
 
 static int write_pack_buf(void *buf, size_t size, void *data)

src/push.c

@@ -582,7 +582,7 @@ static int calculate_work(git_push *push)
 
 static int do_push(git_push *push)
 {
-	int error;
+	int error = 0;
 	git_transport *transport = push->remote->transport;
 
 	if (!transport->push) {
@@ -611,8 +611,6 @@ static int do_push(git_push *push)
 		(error = transport->push(transport, push)) < 0)
 		goto on_error;
 
-	error = 0;
-
 on_error:
 	git_packbuilder_free(push->pb);
 	return error;

src/transports/smart.c

@@ -23,8 +23,13 @@ static int git_smart__recv_cb(gitno_buffer *buf)
 
 	buf->offset += bytes_read;
 
-	if (t->packetsize_cb)
-		t->packetsize_cb(bytes_read, t->packetsize_payload);
+	if (t->packetsize_cb && !t->cancelled.val)
+		if (t->packetsize_cb(bytes_read, t->packetsize_payload)) {
+			git_atomic_set(&t->cancelled, 1);
+
+			giterr_clear();
+			return GIT_EUSER;
+		}
 
 	return (int)(buf->offset - old_len);
 }

src/transports/smart.h

@@ -119,7 +119,7 @@ typedef struct transport_smart_caps {
 		report_status:1;
 } transport_smart_caps;
 
-typedef void (*packetsize_cb)(size_t received, void *payload);
+typedef int (*packetsize_cb)(size_t received, void *payload);
 
 typedef struct {
 	git_transport parent;

src/transports/smart_protocol.c

@@ -425,7 +425,7 @@ struct network_packetsize_payload
 	size_t last_fired_bytes;
 };
 
-static void network_packetsize(size_t received, void *payload)
+static int network_packetsize(size_t received, void *payload)
 {
 	struct network_packetsize_payload *npp = (struct network_packetsize_payload*)payload;
 
@@ -435,8 +435,12 @@ static void network_packetsize(size_t received, void *payload)
 	/* Fire notification if the threshold is reached */
 	if ((npp->stats->received_bytes - npp->last_fired_bytes) > NETWORK_XFER_THRESHOLD) {
 		npp->last_fired_bytes = npp->stats->received_bytes;
-		npp->callback(npp->stats, npp->payload);
+
+		if(npp->callback(npp->stats, npp->payload))
+			return GIT_EUSER;
 	}
+
+	return 0;
 }
 
 int git_smart__download_pack(
@@ -450,7 +454,7 @@ int git_smart__download_pack(
 	gitno_buffer *buf = &t->buffer;
 	git_odb *odb;
 	struct git_odb_writepack *writepack = NULL;
-	int error = -1;
+	int error = 0;
 	struct network_packetsize_payload npp = {0};
 
 	memset(stats, 0, sizeof(git_transfer_progress));
@@ -463,13 +467,14 @@ int git_smart__download_pack(
 		t->packetsize_payload = &npp;
 
 		/* We might have something in the buffer already from negotiate_fetch */
-		if (t->buffer.offset > 0)
-			t->packetsize_cb(t->buffer.offset, t->packetsize_payload);
+		if (t->buffer.offset > 0 && !t->cancelled.val)
+			if(t->packetsize_cb(t->buffer.offset, t->packetsize_payload))
+				git_atomic_set(&t->cancelled, 1);
 	}
 
 	if ((error = git_repository_odb__weakptr(&odb, repo)) < 0 ||
 		((error = git_odb_write_pack(&writepack, odb, progress_cb, progress_payload)) < 0))
-		goto on_error;
+		goto done;
 
 	/*
 	 * If the remote doesn't support the side-band, we can feed
@@ -477,23 +482,29 @@ int git_smart__download_pack(
 	 * check which one belongs there.
 	 */
 	if (!t->caps.side_band && !t->caps.side_band_64k) {
-		if (no_sideband(t, writepack, buf, stats) < 0)
-			goto on_error;
-
-		goto on_success;
+		error = no_sideband(t, writepack, buf, stats);
+		goto done;
 	}
 
 	do {
 		git_pkt *pkt;
 
+		/* Check cancellation before network call */
 		if (t->cancelled.val) {
 			giterr_set(GITERR_NET, "The fetch was cancelled by the user");
 			error = GIT_EUSER;
-			goto on_error;
+			goto done;
 		}
 
-		if (recv_pkt(&pkt, buf) < 0)
-			goto on_error;
+		if ((error = recv_pkt(&pkt, buf)) < 0)
+			goto done;
+
+		/* Check cancellation after network call */
+		if (t->cancelled.val) {
+			giterr_set(GITERR_NET, "The fetch was cancelled by the user");
+			error = GIT_EUSER;
+			goto done;
+		}
 
 		if (pkt->type == GIT_PKT_PROGRESS) {
 			if (t->progress_cb) {
@@ -507,7 +518,7 @@ int git_smart__download_pack(
 
 			git__free(pkt);
 			if (error < 0)
-				goto on_error;
+				goto done;
 		} else if (pkt->type == GIT_PKT_FLUSH) {
 			/* A flush indicates the end of the packfile */
 			git__free(pkt);
@@ -515,13 +526,10 @@ int git_smart__download_pack(
 		}
 	} while (1);
 
-	if (writepack->commit(writepack, stats) < 0)
-		goto on_error;
-
-on_success:
-	error = 0;
+	if ((error = writepack->commit(writepack, stats)) < 0)
+		goto done;
 
-on_error:
+done:
 	if (writepack)
 		writepack->free(writepack);
 
@@ -828,7 +836,10 @@ static int stream_thunk(void *buf, size_t size, void *data)
 
 		if ((current_time - payload->last_progress_report_time) >= MIN_PROGRESS_UPDATE_INTERVAL) {
 			payload->last_progress_report_time = current_time;
-			payload->cb(payload->pb->nr_written, payload->pb->nr_objects, payload->last_bytes, payload->cb_payload);
+			if(payload->cb(payload->pb->nr_written, payload->pb->nr_objects, payload->last_bytes, payload->cb_payload)) {
+				giterr_clear();
+				error = GIT_EUSER;
+			}
 		}
 	}
 
@@ -840,7 +851,7 @@ int git_smart__push(git_transport *transport, git_push *push)
 	transport_smart *t = (transport_smart *)transport;
 	struct push_packbuilder_payload packbuilder_payload = {0};
 	git_buf pktline = GIT_BUF_INIT;
-	int error = -1, need_pack = 0;
+	int error = 0, need_pack = 0;
 	push_spec *spec;
 	unsigned int i;
 
@@ -882,20 +893,21 @@ int git_smart__push(git_transport *transport, git_push *push)
 		}
 	}
 
-	if (git_smart__get_push_stream(t, &packbuilder_payload.stream) < 0 ||
-		gen_pktline(&pktline, push) < 0 ||
-		packbuilder_payload.stream->write(packbuilder_payload.stream, git_buf_cstr(&pktline), git_buf_len(&pktline)) < 0)
-		goto on_error;
+	if ((error = git_smart__get_push_stream(t, &packbuilder_payload.stream)) < 0 ||
+		(error = gen_pktline(&pktline, push)) < 0 ||
+		(error = packbuilder_payload.stream->write(packbuilder_payload.stream, git_buf_cstr(&pktline), git_buf_len(&pktline))) < 0)
+		goto done;
 
-	if (need_pack && git_packbuilder_foreach(push->pb, &stream_thunk, &packbuilder_payload) < 0)
-		goto on_error;
+	if (need_pack &&
+		(error = git_packbuilder_foreach(push->pb, &stream_thunk, &packbuilder_payload)) < 0)
+		goto done;
 
 	/* If we sent nothing or the server doesn't support report-status, then
 	 * we consider the pack to have been unpacked successfully */
 	if (!push->specs.length || !push->report_status)
 		push->unpack_ok = 1;
-	else if (parse_report(&t->buffer, push) < 0)
-		goto on_error;
+	else if ((error = parse_report(&t->buffer, push)) < 0)
+		goto done;
 
 	/* If progress is being reported write the final report */
 	if (push->transfer_progress_cb) {
@@ -903,13 +915,10 @@ int git_smart__push(git_transport *transport, git_push *push)
 	}
 
 	if (push->status.length &&
-		update_refs_from_report(&t->refs, &push->specs, &push->status) < 0)
-		goto on_error;
+		(error = update_refs_from_report(&t->refs, &push->specs, &push->status)) < 0)
+		goto done;
 
-	error = 0;
-
-on_error:
+done:
 	git_buf_free(&pktline);
-
 	return error;
 }

tests-clar/online/push.c

@@ -349,16 +349,18 @@ void test_online_push__cleanup(void)
 	cl_git_sandbox_cleanup();
 }
 
-static void push_pack_progress_cb(int stage, unsigned int current, unsigned int total, void* payload)
+static int push_pack_progress_cb(int stage, unsigned int current, unsigned int total, void* payload)
 {
 	int *was_called = (int *) payload;
 	*was_called = 1;
+	return 0;
 }
 
-static void push_transfer_progress_cb(unsigned int current, unsigned int total, size_t bytes, void* payload)
+static int push_transfer_progress_cb(unsigned int current, unsigned int total, size_t bytes, void* payload)
 {
 	int *was_called = (int *) payload;
 	*was_called = 1;
+	return 0;
 }
 
 /**