Reduce allocations in SSL writev implementations

This change reduces memory allocations by retaining the writev buffer
across invocations. Memory is only freed/allocated if the buffer too
small.

Signed-off-by: Michael Steinert <mike.steinert@gmail.com>

4 files changed, 58 insertions, 29 deletions

diff --git a/librabbitmq/amqp-cyassl.c b/librabbitmq/amqp-cyassl.c
index f8e4d40..960e209 100644
--- a/librabbitmq/amqp-cyassl.c
+++ b/librabbitmq/amqp-cyassl.c
@@ -32,6 +32,8 @@
 struct amqp_ssl_socket_context {
 	CYASSL_CTX *ctx;
 	CYASSL *ssl;
+	char *buffer;
+	size_t length;
 };
 
 static ssize_t
@@ -52,26 +54,30 @@ amqp_ssl_socket_writev(AMQP_UNUSED int sockfd,
 		       void *user_data)
 {
 	struct amqp_ssl_socket_context *self = user_data;
-	char *buffer, *bufferp;
 	ssize_t written = -1;
+	char *bufferp;
 	size_t bytes;
 	int i;
 	bytes = 0;
 	for (i = 0; i < iovcnt; ++i) {
 		bytes += iov[i].iov_len;
 	}
-	buffer = malloc(bytes);
-	if (!buffer) {
-		goto exit;
+	if (self->length < bytes) {
+		free(self->buffer);
+		self->buffer = malloc(bytes);
+		if (!self->buffer) {
+			self->length = 0;
+			goto exit;
+		}
+		self->length = bytes;
 	}
-	bufferp = buffer;
+	bufferp = self->buffer;
 	for (i = 0; i < iovcnt; ++i) {
 		memcpy(bufferp, iov[i].iov_base, iov[i].iov_len);
 		bufferp += iov[i].iov_len;
 	}
-	written = CyaSSL_write(self->ssl, buffer, bytes);
+	written = CyaSSL_write(self->ssl, self->buffer, bytes);
 exit:
-	free(buffer);
 	return written;
 }
 
@@ -95,6 +101,7 @@ amqp_ssl_socket_close(int sockfd,
 	if (self) {
 		CyaSSL_free(self->ssl);
 		CyaSSL_CTX_free(self->ctx);
+		free(self->buffer);
 		free(self);
 	}
 	if (sockfd >= 0) {
diff --git a/librabbitmq/amqp-gnutls.c b/librabbitmq/amqp-gnutls.c
index a435371..3268007 100644
--- a/librabbitmq/amqp-gnutls.c
+++ b/librabbitmq/amqp-gnutls.c
@@ -34,6 +34,8 @@ struct amqp_ssl_socket_context {
 	gnutls_session_t session;
 	gnutls_certificate_credentials_t credentials;
 	char *host;
+	char *buffer;
+	size_t length;
 };
 
 static ssize_t
@@ -54,26 +56,30 @@ amqp_ssl_socket_writev(AMQP_UNUSED int sockfd,
 		       void *user_data)
 {
 	struct amqp_ssl_socket_context *self = user_data;
-	char *buffer, *bufferp;
 	ssize_t written = -1;
+	char *bufferp;
 	size_t bytes;
 	int i;
 	bytes = 0;
 	for (i = 0; i < iovcnt; ++i) {
 		bytes += iov[i].iov_len;
 	}
-	buffer = malloc(bytes);
-	if (!buffer) {
-		goto exit;
+	if (self->length < bytes) {
+		free(self->buffer);
+		self->buffer = malloc(bytes);
+		if (!self->buffer) {
+			self->length = 0;
+			goto exit;
+		}
+		self->length = 0;
 	}
-	bufferp = buffer;
+	bufferp = self->buffer;
 	for (i = 0; i < iovcnt; ++i) {
 		memcpy(bufferp, iov[i].iov_base, iov[i].iov_len);
 		bufferp += iov[i].iov_len;
 	}
-	written = gnutls_record_send(self->session, buffer, bytes);
+	written = gnutls_record_send(self->session, self->buffer, bytes);
 exit:
-	free(buffer);
 	return written;
 }
 
@@ -101,6 +107,7 @@ amqp_ssl_socket_close(int sockfd,
 		gnutls_deinit(self->session);
 		gnutls_certificate_free_credentials(self->credentials);
 		free(self->host);
+		free(self->buffer);
 		free(self);
 	}
 	return status;
diff --git a/librabbitmq/amqp-openssl.c b/librabbitmq/amqp-openssl.c
index d97aa4c..781ce8a 100644
--- a/librabbitmq/amqp-openssl.c
+++ b/librabbitmq/amqp-openssl.c
@@ -37,6 +37,8 @@
 struct amqp_ssl_socket_context {
 	BIO *bio;
 	SSL_CTX *ctx;
+	char *buffer;
+	size_t length;
 };
 
 static ssize_t
@@ -74,26 +76,30 @@ amqp_ssl_socket_writev(AMQP_UNUSED int sockfd,
 		       void *user_data)
 {
 	struct amqp_ssl_socket_context *self = user_data;
-	char *buffer, *bufferp;
 	ssize_t written = -1;
+	char *bufferp;
 	size_t bytes;
 	int i;
 	bytes = 0;
 	for (i = 0; i < iovcnt; ++i) {
 		bytes += iov[i].iov_len;
 	}
-	buffer = malloc(bytes);
-	if (!buffer) {
-		goto exit;
+	if (self->length < bytes) {
+		free(self->buffer);
+		self->buffer = malloc(bytes);
+		if (!self->buffer) {
+			self->length = 0;
+			goto exit;
+		}
+		self->length = bytes;
 	}
-	bufferp = buffer;
+	bufferp = self->buffer;
 	for (i = 0; i < iovcnt; ++i) {
 		memcpy(bufferp, iov[i].iov_base, iov[i].iov_len);
 		bufferp += iov[i].iov_len;
 	}
-	written = amqp_ssl_socket_send(sockfd, buffer, bytes, 0, self);
+	written = amqp_ssl_socket_send(sockfd, self->buffer, bytes, 0, self);
 exit:
-	free(buffer);
 	return written;
 }
 
@@ -131,6 +137,7 @@ amqp_ssl_socket_close(int sockfd,
 	if (self) {
 		BIO_free_all(self->bio);
 		SSL_CTX_free(self->ctx);
+		free(self->buffer);
 		free(self);
 	}
 	return 0 > sockfd ? -1 : 0;
diff --git a/librabbitmq/amqp-polarssl.c b/librabbitmq/amqp-polarssl.c
index e55aa00..55dbc43 100644
--- a/librabbitmq/amqp-polarssl.c
+++ b/librabbitmq/amqp-polarssl.c
@@ -41,6 +41,8 @@ struct amqp_ssl_socket_context {
 	x509_cert *cert;
 	ssl_context *ssl;
 	ssl_session *session;
+	char *buffer;
+	size_t length;
 };
 
 static ssize_t
@@ -61,26 +63,31 @@ amqp_ssl_socket_writev(AMQP_UNUSED int sockfd,
 		       void *user_data)
 {
 	struct amqp_ssl_socket_context *self = user_data;
-	char *buffer, *bufferp;
 	ssize_t written = -1;
+	char *bufferp;
 	size_t bytes;
 	int i;
 	bytes = 0;
 	for (i = 0; i < iovcnt; ++i) {
 		bytes += iov[i].iov_len;
 	}
-	buffer = malloc(bytes);
-	if (!buffer) {
-		goto exit;
+	if (self->length < bytes) {
+		free(self->buffer);
+		self->buffer = malloc(bytes);
+		if (!self->buffer) {
+			self->length = 0;
+			goto exit;
+		}
+		self->length = bytes;
 	}
-	bufferp = buffer;
+	bufferp = self->buffer;
 	for (i = 0; i < iovcnt; ++i) {
 		memcpy(bufferp, iov[i].iov_base, iov[i].iov_len);
 		bufferp += iov[i].iov_len;
 	}
-	written = ssl_write(self->ssl, (const unsigned char *)buffer, bytes);
+	written = ssl_write(self->ssl, (const unsigned char *)self->buffer,
+			    bytes);
 exit:
-	free(buffer);
 	return written;
 }
 
@@ -113,11 +120,12 @@ amqp_ssl_socket_close(int sockfd,
 		ssl_free(self->ssl);
 		free(self->ssl);
 		free(self->session);
-		free(self);
+		free(self->buffer);
 		if (self->sockfd >= 0) {
 			net_close(sockfd);
 			status = 0;
 		}
+		free(self);
 	}
 	return status;
 }