path: root/pkg/sshfs/patch/0002-Use-a-compact-array-and-free-list-for-requests.patch

From 9e0a40fee13134d47980f01c68ec3b10e0d31bc3 Mon Sep 17 00:00:00 2001
From: Michael Forney <mforney@mforney.org>
Date: Sun, 5 Jun 2016 17:25:36 -0700
Subject: [PATCH] Use a compact array and free list for requests

---
 sshfs.c | 126 +++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 80 insertions(+), 46 deletions(-)

diff --git a/sshfs.c b/sshfs.c
index d4d624d..92b893e 100644
--- a/sshfs.c
+++ b/sshfs.c
@@ -171,6 +171,17 @@ struct request {
 	struct list_head list;
 };
 
+union request_entry {
+	struct request *req;
+	uintptr_t next;
+};
+
+struct request_table {
+	union request_entry *entries;
+	int len, cap;
+	uint32_t free;
+};
+
 struct sshfs_io {
 	int num_reqs;
 	pthread_cond_t finished;
@@ -253,7 +264,7 @@ struct sshfs {
 	int slave;
 	char *host;
 	char *base_path;
-	GHashTable *reqtab;
+	struct request_table reqtab;
 	pthread_mutex_t lock;
 	pthread_mutex_t lock_write;
 	int processing_thread_started;
@@ -1171,12 +1182,6 @@ static int do_write(struct iovec *iov, size_t count)
 	return 0;
 }
 
-static uint32_t sftp_get_id(void)
-{
-	static uint32_t idctr;
-	return idctr++;
-}
-
 static void buf_to_iov(const struct buffer *buf, struct iovec *iov)
 {
 	iov->iov_base = buf->p;
@@ -1269,6 +1274,43 @@ static void request_free(struct request *req)
 	g_free(req);
 }
 
+static int request_table_insert(struct request_table *reqtab, struct request *req)
+{
+	union request_entry *entries;
+	size_t cap;
+
+	if (reqtab->free) {
+		req->id = reqtab->free;
+		reqtab->free = reqtab->entries[req->id-1].next >> 1;
+	} else {
+		if (reqtab->len == reqtab->cap) {
+			cap = reqtab->cap * 2 + 1;
+			entries = realloc(reqtab->entries, cap * sizeof(reqtab->entries[0]));
+			if (!entries)
+				return -1;
+			reqtab->cap = cap;
+			reqtab->entries = entries;
+		}
+		req->id = ++reqtab->len;
+	}
+
+	reqtab->entries[req->id-1].req = req;
+	return 0;
+}
+
+static struct request *request_table_lookup(struct request_table *reqtab, uint32_t id)
+{
+	if (reqtab->entries[id-1].next & 1)
+		return NULL;
+	return reqtab->entries[id-1].req;
+}
+
+static void request_table_remove(struct request_table *reqtab, uint32_t id)
+{
+	reqtab->entries[id-1].next = (reqtab->free << 1) | 1;
+	reqtab->free = id;
+}
+
 static void chunk_free(struct read_chunk *chunk)
 {
 	while (!list_empty(&chunk->reqs)) {
@@ -1298,22 +1340,6 @@ static void chunk_put_locked(struct read_chunk *chunk)
 	pthread_mutex_unlock(&sshfs.lock);
 }
 
-static int clean_req(void *key_, struct request *req, gpointer user_data_)
-{
-	(void) key_;
-	(void) user_data_;
-
-	req->error = -EIO;
-	if (req->want_reply)
-		sem_post(&req->ready);
-	else {
-		if (req->end_func)
-			req->end_func(req);
-		request_free(req);
-	}
-	return TRUE;
-}
-
 static int process_one_request(void)
 {
 	int res;
@@ -1330,8 +1356,7 @@ static int process_one_request(void)
 		return -1;
 
 	pthread_mutex_lock(&sshfs.lock);
-	req = (struct request *)
-		g_hash_table_lookup(sshfs.reqtab, GUINT_TO_POINTER(id));
+	req = request_table_lookup(&sshfs.reqtab, id);
 	if (req == NULL)
 		fprintf(stderr, "request %i not found\n", id);
 	else {
@@ -1343,7 +1368,7 @@ static int process_one_request(void)
 		    sshfs.outstanding_len <= sshfs.max_outstanding_len) {
 			pthread_cond_broadcast(&sshfs.outstanding_cond);
 		}
-		g_hash_table_remove(sshfs.reqtab, GUINT_TO_POINTER(id));
+		request_table_remove(&sshfs.reqtab, id);
 	}
 	pthread_mutex_unlock(&sshfs.lock);
 	if (req != NULL) {
@@ -1404,6 +1429,9 @@ static void close_conn(void)
 
 static void *process_requests(void *data_)
 {
+	int i;
+	struct request *req;
+
 	(void) data_;
 
 	while (1) {
@@ -1414,7 +1442,20 @@ static void *process_requests(void *data_)
 	pthread_mutex_lock(&sshfs.lock);
 	sshfs.processing_thread_started = 0;
 	close_conn();
-	g_hash_table_foreach_remove(sshfs.reqtab, (GHRFunc) clean_req, NULL);
+	for (i = 0; i < sshfs.reqtab.len; ++i) {
+		if (sshfs.reqtab.entries[i].next & 1)
+			continue;
+		req = sshfs.reqtab.entries[i].req;
+		req->error = -EIO;
+		if (req->want_reply)
+			sem_post(&req->ready);
+		else {
+			if (req->end_func)
+				req->end_func(req);
+			request_free(req);
+		}
+		request_table_remove(&sshfs.reqtab, i + 1);
+	}
 	sshfs.connver ++;
 	sshfs.outstanding_len = 0;
 	pthread_cond_broadcast(&sshfs.outstanding_cond);
@@ -1562,7 +1603,6 @@ static int sftp_error_to_errno(uint32_t error)
 static void sftp_detect_uid()
 {
 	int flags;
-	uint32_t id = sftp_get_id();
 	uint32_t replid;
 	uint8_t type;
 	struct buffer buf;
@@ -1572,7 +1612,7 @@ static void sftp_detect_uid()
 	buf_init(&buf, 5);
 	buf_add_string(&buf, ".");
 	buf_to_iov(&buf, &iov[0]);
-	if (sftp_send_iov(SSH_FXP_STAT, id, iov, 1) == -1)
+	if (sftp_send_iov(SSH_FXP_STAT, 0, iov, 1) == -1)
 		goto out;
 	buf_clear(&buf);
 	if (sftp_read(&type, &buf) == -1)
@@ -1583,7 +1623,7 @@ static void sftp_detect_uid()
 	}
 	if (buf_get_uint32(&buf, &replid) == -1)
 		goto out;
-	if (replid != id) {
+	if (replid != 0) {
 		fprintf(stderr, "bad reply ID\n");
 		goto out;
 	}
@@ -1618,7 +1658,6 @@ out:
 static int sftp_check_root(const char *base_path)
 {
 	int flags;
-	uint32_t id = sftp_get_id();
 	uint32_t replid;
 	uint8_t type;
 	struct buffer buf;
@@ -1630,7 +1669,7 @@ static int sftp_check_root(const char *base_path)
 	buf_init(&buf, 0);
 	buf_add_string(&buf, remote_dir);
 	buf_to_iov(&buf, &iov[0]);
-	if (sftp_send_iov(SSH_FXP_LSTAT, id, iov, 1) == -1)
+	if (sftp_send_iov(SSH_FXP_LSTAT, 0, iov, 1) == -1)
 		goto out;
 	buf_clear(&buf);
 	if (sftp_read(&type, &buf) == -1)
@@ -1641,7 +1680,7 @@ static int sftp_check_root(const char *base_path)
 	}
 	if (buf_get_uint32(&buf, &replid) == -1)
 		goto out;
-	if (replid != id) {
+	if (replid != 0) {
 		fprintf(stderr, "bad reply ID\n");
 		goto out;
 	}
@@ -1831,7 +1870,6 @@ static int sftp_request_send(uint8_t type, struct iovec *iov, size_t count,
                              struct request **reqp)
 {
 	int err;
-	uint32_t id;
 	struct request *req = g_new0(struct request, 1);
 
 	req->want_reply = want_reply;
@@ -1842,8 +1880,6 @@ static int sftp_request_send(uint8_t type, struct iovec *iov, size_t count,
 	pthread_mutex_lock(&sshfs.lock);
 	if (begin_func)
 		begin_func(req);
-	id = sftp_get_id();
-	req->id = id;
 	err = start_processing_thread();
 	if (err) {
 		pthread_mutex_unlock(&sshfs.lock);
@@ -1854,21 +1890,24 @@ static int sftp_request_send(uint8_t type, struct iovec *iov, size_t count,
 	while (sshfs.outstanding_len > sshfs.max_outstanding_len)
 		pthread_cond_wait(&sshfs.outstanding_cond, &sshfs.lock);
 
-	g_hash_table_insert(sshfs.reqtab, GUINT_TO_POINTER(id), req);
+	if (request_table_insert(&sshfs.reqtab, req) < 0)
+		abort();
 	if (sshfs.debug) {
 		gettimeofday(&req->start, NULL);
 		sshfs.num_sent++;
 		sshfs.bytes_sent += req->len;
 	}
-	DEBUG("[%05i] %s\n", id, type_name(type));
+	DEBUG("[%05i] %s\n", req->id, type_name(type));
 	pthread_mutex_unlock(&sshfs.lock);
 
 	err = -EIO;
-	if (sftp_send_iov(type, id, iov, count) == -1) {
+	if (sftp_send_iov(type, req->id, iov, count) == -1) {
 		gboolean rmed;
 
 		pthread_mutex_lock(&sshfs.lock);
-		rmed = g_hash_table_remove(sshfs.reqtab, GUINT_TO_POINTER(id));
+		rmed = !!request_table_lookup(&sshfs.reqtab, req->id);
+		if (rmed)
+			request_table_remove(&sshfs.reqtab, req->id);
 		pthread_mutex_unlock(&sshfs.lock);
 
 		if (!rmed && !want_reply) {
@@ -2041,7 +2080,7 @@ static int sftp_readdir_send(struct request **req, struct buffer *handle)
 
 static int sshfs_req_pending(struct request *req)
 {
-	if (g_hash_table_lookup(sshfs.reqtab, GUINT_TO_POINTER(req->id)))
+	if (request_table_lookup(&sshfs.reqtab, req->id))
 		return 1;
 	else
 		return 0;
@@ -3312,11 +3351,6 @@ static int processing_init(void)
 	pthread_mutex_init(&sshfs.lock, NULL);
 	pthread_mutex_init(&sshfs.lock_write, NULL);
 	pthread_cond_init(&sshfs.outstanding_cond, NULL);
-	sshfs.reqtab = g_hash_table_new(NULL, NULL);
-	if (!sshfs.reqtab) {
-		fprintf(stderr, "failed to create hash table\n");
-		return -1;
-	}
 	return 0;
 }
 
-- 
2.24.0