(trunk libT) avoid about 75% of the strdup/malloc/frees in benc by using a union of char* and a small string buffer, and using the buffer if the string is small enough

libtransmission/bencode.c

@@ -358,9 +358,30 @@ tr_bencLoad( const void * buf_in,
 ****
 ***/
 
+/* returns true if the given string length would fit in our string buffer */
+static TR_INLINE int
+stringFitsInBuffer( const tr_benc * val, int len )
+{
+    return len < (int)sizeof( val->val.s.str.buf );
+}
+
+/* returns true if the benc's string was malloced.
+ * this occurs when the string is too long for our string buffer */
+static TR_INLINE int
+stringIsAlloced( const tr_benc * val )
+{
+    return !stringFitsInBuffer( val, val->val.s.len );
+}
+
+/* returns a const pointer to the benc's string */
+static TR_INLINE const char*
+getStr( const tr_benc* val )
+{
+    return stringIsAlloced(val) ? val->val.s.str.ptr : val->val.s.str.buf;
+}
+
 static int
-dictIndexOf( const tr_benc * val,
-             const char *    key )
+dictIndexOf( const tr_benc * val, const char * key )
 {
     if( tr_bencIsDict( val ) )
     {
@@ -370,10 +391,9 @@ dictIndexOf( const tr_benc * val,
         for( i = 0; ( i + 1 ) < val->val.l.count; i += 2 )
         {
             const tr_benc * child = val->val.l.vals + i;
-
             if( ( child->type == TR_TYPE_STR )
-              && ( child->val.s.i == len )
-              && !memcmp( child->val.s.s, key, len ) )
+              && ( child->val.s.len == len )
+              && !memcmp( getStr(child), key, len ) )
                 return i;
         }
     }
@@ -444,7 +464,7 @@ tr_bencGetStr( const tr_benc * val,
     const int success = tr_bencIsString( val );
 
     if( success )
-        *setme = val->val.s.s;
+        *setme = getStr( val );
 
     return success;
 }
@@ -452,6 +472,7 @@ tr_bencGetStr( const tr_benc * val,
 tr_bool
 tr_bencGetBool( const tr_benc * val, tr_bool * setme )
 {
+    const char * str;
     tr_bool success = FALSE;
 
     if(( success = tr_bencIsBool( val )))
@@ -461,9 +482,9 @@ tr_bencGetBool( const tr_benc * val, tr_bool * setme )
         if(( success = ( val->val.i==0 || val->val.i==1 ) ))
             *setme = val->val.i!=0;
 
-    if( !success && tr_bencIsString( val ) )
-        if(( success = ( !strcmp(val->val.s.s,"true") || !strcmp(val->val.s.s,"false"))))
-            *setme = !strcmp(val->val.s.s,"true");
+    if( !success && tr_bencGetStr( val, &str ) )
+        if(( success = ( !strcmp(str,"true") || !strcmp(str,"false"))))
+            *setme = !strcmp(str,"true");
 
     return success;
 }
@@ -488,10 +509,10 @@ tr_bencGetReal( const tr_benc * val, double * setme )
         /* the json spec requires a '.' decimal point regardless of locale */
         tr_strlcpy( locale, setlocale( LC_NUMERIC, NULL ), sizeof( locale ) );
         setlocale( LC_NUMERIC, "POSIX" );
-        d  = strtod( val->val.s.s, &endptr );
+        d  = strtod( getStr(val), &endptr );
         setlocale( LC_NUMERIC, locale );
 
-        if(( success = ( val->val.s.s != endptr ) && !*endptr ))
+        if(( success = ( getStr(val) != endptr ) && !*endptr ))
             *setme = d;
     }
 
@@ -545,8 +566,8 @@ tr_bencDictFindRaw( tr_benc         * dict,
     const tr_bool found = tr_bencDictFindType( dict, key, TR_TYPE_STR, &child );
 
     if( found ) {
-        *setme_raw = (uint8_t*) child->val.s.s;
-        *setme_len = child->val.s.i;
+        *setme_raw = (uint8_t*) getStr(child);
+        *setme_len = child->val.s.len;
     }
 
     return found;
@@ -557,30 +578,31 @@ tr_bencDictFindRaw( tr_benc         * dict,
 ***/
 
 void
-tr_bencInitRaw( tr_benc *    val,
-                const void * src,
-                size_t       byteCount )
+tr_bencInitRaw( tr_benc * val, const void * src, size_t byteCount )
 {
     tr_bencInit( val, TR_TYPE_STR );
-    val->val.s.i = byteCount;
-    val->val.s.s = tr_memdup( src, byteCount );
+
+    if( stringFitsInBuffer( val, val->val.s.len = byteCount ))
+        memcpy( val->val.s.str.buf, src, byteCount );
+    else
+        val->val.s.str.ptr = tr_memdup( src, byteCount );
 }
 
 void
-tr_bencInitStr( tr_benc *    val,
-                const void * str,
-                int          len )
+tr_bencInitStr( tr_benc * val, const void * str, int len )
 {
     tr_bencInit( val, TR_TYPE_STR );
 
-    val->val.s.s = tr_strndup( str, len );
-
-    if( val->val.s.s == NULL )
-        val->val.s.i = 0;
+    if( str == NULL )
+        len = 0;
     else if( len < 0 )
-        val->val.s.i = strlen( val->val.s.s );
-    else
-        val->val.s.i = len;
+        len = strlen( str );
+
+    if( stringFitsInBuffer( val, val->val.s.len = len )) {
+        memcpy( val->val.s.str.buf, str, len );
+        val->val.s.str.buf[len] = '\0';
+    } else
+        val->val.s.str.ptr = tr_strndup( str, len );
 }
 
 void
@@ -764,9 +786,10 @@ tr_bencDictAddStr( tr_benc * dict, const char * key, const char * val )
 
     /* see if it already exists, and if so, try to reuse it */
     if(( child = tr_bencDictFind( dict, key ))) {
-        if( tr_bencIsString( child ) )
-            tr_free( child->val.s.s );
-        else {
+        if( tr_bencIsString( child ) ) {
+            if( stringIsAlloced( child ) )
+                tr_free( child->val.s.str.ptr );
+        } else {
             tr_bencDictRemove( dict, key );
             child = NULL;
         }
@@ -885,7 +908,7 @@ nodeNewDict( const tr_benc * val )
     indices = tr_new( struct KeyIndex, nKeys );
     for( i = j = 0; i < ( nKeys * 2 ); i += 2, ++j )
     {
-        indices[j].key = val->val.l.vals[i].val.s.s;
+        indices[j].key = getStr(&val->val.l.vals[i]);
         indices[j].index = i;
     }
     qsort( indices, j, sizeof( struct KeyIndex ), compareKeyIndex );
@@ -1081,8 +1104,8 @@ saveRealFunc( const tr_benc * val, void * evbuf )
 static void
 saveStringFunc( const tr_benc * val, void * evbuf )
 {
-    evbuffer_add_printf( evbuf, "%lu:", (unsigned long)val->val.s.i );
-    evbuffer_add( evbuf, val->val.s.s, val->val.s.i );
+    evbuffer_add_printf( evbuf, "%lu:", (unsigned long)val->val.s.len );
+    evbuffer_add( evbuf, getStr(val), val->val.s.len );
 }
 
 static void
@@ -1141,7 +1164,8 @@ static void
 freeStringFunc( const tr_benc * val,
                 void *          freeme )
 {
-    tr_ptrArrayAppend( freeme, val->val.s.s );
+    if( stringIsAlloced( val ) )
+        tr_ptrArrayAppend( freeme, val->val.s.str.ptr );
 }
 
 static void
@@ -1302,10 +1326,10 @@ static void
 jsonStringFunc( const tr_benc * val, void * vdata )
 {
     struct jsonWalk * data = vdata;
-    const unsigned char * it = (const unsigned char *) val->val.s.s;
-    const unsigned char * end = it + val->val.s.i;
+    const unsigned char * it = (const unsigned char *) getStr(val);
+    const unsigned char * end = it + val->val.s.len;
 
-    evbuffer_expand( data->out, val->val.s.i + 2 );
+    evbuffer_expand( data->out, val->val.s.len + 2 );
     evbuffer_add( data->out, "\"", 1 );
 
     for( ; it!=end; ++it )

libtransmission/bencode.h

@@ -49,8 +49,6 @@ enum
  * it's included in the header for inlining and composition */
 typedef struct tr_benc
 {
-    char type;
-
     union
     {
         uint8_t b; /* bool type */
@@ -61,17 +59,22 @@ typedef struct tr_benc
 
         struct /* string type */
         {
-            size_t i; /* the string length */
-            char * s; /* the string */
+            size_t len; /* the string length */
+            union {
+                char buf[16]; /* a local buffer */
+                char * ptr; /* alloc'ed string */
+            } str;
         } s;
 
         struct /* list & dict types */
         {
+            struct tr_benc * vals; /* nodes */
             size_t alloc; /* nodes allocated */
             size_t count; /* nodes used */
-            struct tr_benc * vals; /* nodes */
         } l;
     } val;
+
+    char type;
 } tr_benc;
 
 /***