Reduce UTCP memory usage.

Don't allocate a send buffer by default, since an application might only
want to receive data. Also try to shrink the send and receive buffers on
channel close, or even free them if the buffers are empty.

diff --git a/src/utcp.c b/src/utcp.c
index 46d7fd35f065473f0baa1a27fe307ee8795eeebc..c21e7067b89610c17182eae3dce57b58a9dfa274 100644 (file)
--- a/src/utcp.c
+++ b/src/utcp.c
@@ -196,6 +196,16 @@ static bool buffer_wraps(struct buffer *buf) {
 }
 
 static bool buffer_resize(struct buffer *buf, uint32_t newsize) {
+       assert(!buf->external);
+
+       if(!newsize) {
+               free(buf->data);
+               buf->data = NULL;
+               buf->size = 0;
+               buf->offset = 0;
+               return true;
+       }
+
        char *newdata = realloc(buf->data, newsize);
 
        if(!newdata) {
@@ -441,17 +451,40 @@ static void set_buffer_storage(struct buffer *buf, char *data, size_t size) {
                buf->external = true;
        } else if(buf->external) {
                // Transition from external to internal buf
-               size_t minsize = buf->used < DEFAULT_SNDBUFSIZE ? DEFAULT_SNDBUFSIZE : buf->used;
-               data = malloc(minsize);
+               size_t minsize = buf->used <= DEFAULT_SNDBUFSIZE ? DEFAULT_SNDBUFSIZE : buf->used;
 
-               if(!data) {
-                       // Cannot handle this
-                       abort();
+               if(minsize) {
+                       data = malloc(minsize);
+
+                       if(!data) {
+                               // Cannot handle this
+                               abort();
+                       }
+
+                       buffer_transfer(buf, data, minsize);
+                       buf->data = data;
+               } else {
+                       buf->data = NULL;
+                       buf->size = 0;
                }
 
-               buffer_transfer(buf, data, minsize);
-               buf->data = data;
                buf->external = false;
+       } else {
+               // Realloc internal storage
+               size_t minsize = buf->used <= DEFAULT_SNDBUFSIZE ? DEFAULT_SNDBUFSIZE : buf->used;
+
+               if(minsize) {
+                       data = realloc(buf->data, minsize);
+
+                       if(data) {
+                               buf->data = data;
+                               buf->size = minsize;
+                       }
+               } else {
+                       free(buf->data);
+                       buf->data = NULL;
+                       buf->size = 0;
+               }
        }
 }
 
@@ -2075,13 +2108,8 @@ static bool reset_connection(struct utcp_connection *c) {
 }
 
 static void set_reapable(struct utcp_connection *c) {
-       if(c->sndbuf.external) {
-               set_buffer_storage(&c->sndbuf, NULL, DEFAULT_MTU);
-       }
-
-       if(c->rcvbuf.external) {
-               set_buffer_storage(&c->rcvbuf, NULL, DEFAULT_MTU);
-       }
+       set_buffer_storage(&c->sndbuf, NULL, DEFAULT_MTU);
+       set_buffer_storage(&c->rcvbuf, NULL, DEFAULT_MTU);
 
        c->recv = NULL;
        c->poll = NULL;

diff --git a/src/utcp_priv.h b/src/utcp_priv.h
index 531f26578e0dd79b335863aeed14c92beac27ffb..f96b92b58f57039a265e2745f69977b8b09dc137 100644 (file)
--- a/src/utcp_priv.h
+++ b/src/utcp_priv.h
@@ -37,7 +37,7 @@
 #define AUX_TIMESTAMP 4
 
 #define NSACKS 4
-#define DEFAULT_SNDBUFSIZE 4096
+#define DEFAULT_SNDBUFSIZE 0
 #define DEFAULT_MAXSNDBUFSIZE 131072
 #define DEFAULT_RCVBUFSIZE 0
 #define DEFAULT_MAXRCVBUFSIZE 131072