performance and memory reporting improvement - sds take control of it's internal frag (#7875)

This commit has two aspects:
1) improve memory reporting for all the places that use sdsAllocSize to compute
   memory used by a string, in this case it'll include the internal fragmentation.
2) reduce the need for realloc calls by making the sds implicitly take over
   the internal fragmentation of the block it allocated.

src/networking.c

@@ -293,7 +293,7 @@ void _addReplyProtoToList(client *c, const char *s, size_t len) {
         size_t size = len < PROTO_REPLY_CHUNK_BYTES? PROTO_REPLY_CHUNK_BYTES: len;
         tail = zmalloc(size + sizeof(clientReplyBlock));
         /* take over the allocation's internal fragmentation */
-        tail->size = zmalloc_usable(tail) - sizeof(clientReplyBlock);
+        tail->size = zmalloc_usable_size(tail) - sizeof(clientReplyBlock);
         tail->used = len;
         memcpy(tail->buf, s, len);
         listAddNodeTail(c->reply, tail);
@@ -489,7 +489,7 @@ void trimReplyUnusedTailSpace(client *c) {
         tail = zrealloc(tail, tail->used + sizeof(clientReplyBlock));
         /* take over the allocation's internal fragmentation (at least for
          * memory usage tracking) */
-        tail->size = zmalloc_usable(tail) - sizeof(clientReplyBlock);
+        tail->size = zmalloc_usable_size(tail) - sizeof(clientReplyBlock);
         c->reply_bytes = c->reply_bytes + tail->size - old_size;
         listNodeValue(ln) = tail;
     }
@@ -541,7 +541,7 @@ void setDeferredAggregateLen(client *c, void *node, long length, char prefix) {
         /* Create a new node */
         clientReplyBlock *buf = zmalloc(lenstr_len + sizeof(clientReplyBlock));
         /* Take over the allocation's internal fragmentation */
-        buf->size = zmalloc_usable(buf) - sizeof(clientReplyBlock);
+        buf->size = zmalloc_usable_size(buf) - sizeof(clientReplyBlock);
         buf->used = lenstr_len;
         memcpy(buf->buf, lenstr, lenstr_len);
         listNodeValue(ln) = buf;

src/sds.c

@@ -73,6 +73,20 @@ static inline char sdsReqType(size_t string_size) {
 #endif
 }
 
+static inline size_t sdsTypeMaxSize(char type) {
+    if (type == SDS_TYPE_5)
+        return (1<<5) - 1;
+    if (type == SDS_TYPE_8)
+        return (1<<8) - 1;
+    if (type == SDS_TYPE_16)
+        return (1<<16) - 1;
+#if (LONG_MAX == LLONG_MAX)
+    if (type == SDS_TYPE_32)
+        return (1ll<<32) - 1;
+#endif
+    return -1; /* this is equivalent to the max SDS_TYPE_64 or SDS_TYPE_32 */
+}
+
 /* Create a new sds string with the content specified by the 'init' pointer
  * and 'initlen'.
  * If NULL is used for 'init' the string is initialized with zero bytes.
@@ -95,8 +109,9 @@ sds sdsnewlen(const void *init, size_t initlen) {
     if (type == SDS_TYPE_5 && initlen == 0) type = SDS_TYPE_8;
     int hdrlen = sdsHdrSize(type);
     unsigned char *fp; /* flags pointer. */
+    size_t usable;
 
-    sh = s_malloc(hdrlen+initlen+1);
+    sh = s_malloc_usable(hdrlen+initlen+1, &usable);
     if (sh == NULL) return NULL;
     if (init==SDS_NOINIT)
         init = NULL;
@@ -104,6 +119,9 @@ sds sdsnewlen(const void *init, size_t initlen) {
         memset(sh, 0, hdrlen+initlen+1);
     s = (char*)sh+hdrlen;
     fp = ((unsigned char*)s)-1;
+    usable = usable-hdrlen-1;
+    if (usable > sdsTypeMaxSize(type))
+        usable = sdsTypeMaxSize(type);
     switch(type) {
         case SDS_TYPE_5: {
             *fp = type | (initlen << SDS_TYPE_BITS);
@@ -112,28 +130,28 @@ sds sdsnewlen(const void *init, size_t initlen) {
         case SDS_TYPE_8: {
             SDS_HDR_VAR(8,s);
             sh->len = initlen;
-            sh->alloc = initlen;
+            sh->alloc = usable;
             *fp = type;
             break;
         }
         case SDS_TYPE_16: {
             SDS_HDR_VAR(16,s);
             sh->len = initlen;
-            sh->alloc = initlen;
+            sh->alloc = usable;
             *fp = type;
             break;
         }
         case SDS_TYPE_32: {
             SDS_HDR_VAR(32,s);
             sh->len = initlen;
-            sh->alloc = initlen;
+            sh->alloc = usable;
             *fp = type;
             break;
         }
         case SDS_TYPE_64: {
             SDS_HDR_VAR(64,s);
             sh->len = initlen;
-            sh->alloc = initlen;
+            sh->alloc = usable;
             *fp = type;
             break;
         }
@@ -207,6 +225,7 @@ sds sdsMakeRoomFor(sds s, size_t addlen) {
     size_t len, newlen;
     char type, oldtype = s[-1] & SDS_TYPE_MASK;
     int hdrlen;
+    size_t usable;
 
     /* Return ASAP if there is enough space left. */
     if (avail >= addlen) return s;
@@ -228,13 +247,13 @@ sds sdsMakeRoomFor(sds s, size_t addlen) {
 
     hdrlen = sdsHdrSize(type);
     if (oldtype==type) {
-        newsh = s_realloc(sh, hdrlen+newlen+1);
+        newsh = s_realloc_usable(sh, hdrlen+newlen+1, &usable);
         if (newsh == NULL) return NULL;
         s = (char*)newsh+hdrlen;
     } else {
         /* Since the header size changes, need to move the string forward,
          * and can't use realloc */
-        newsh = s_malloc(hdrlen+newlen+1);
+        newsh = s_malloc_usable(hdrlen+newlen+1, &usable);
         if (newsh == NULL) return NULL;
         memcpy((char*)newsh+hdrlen, s, len+1);
         s_free(sh);
@@ -242,7 +261,10 @@ sds sdsMakeRoomFor(sds s, size_t addlen) {
         s[-1] = type;
         sdssetlen(s, len);
     }
-    sdssetalloc(s, newlen);
+    usable = usable-hdrlen-1;
+    if (usable > sdsTypeMaxSize(type))
+        usable = sdsTypeMaxSize(type);
+    sdssetalloc(s, usable);
     return s;
 }
 

src/sdsalloc.h

@@ -43,5 +43,8 @@
 #define s_malloc zmalloc
 #define s_realloc zrealloc
 #define s_free zfree
+#define s_malloc_usable zmalloc_usable
+#define s_realloc_usable zrealloc_usable
+#define s_free_usable zfree_usable
 
 #endif

src/zmalloc.c

@@ -99,6 +99,21 @@ void *zmalloc(size_t size) {
 #endif
 }
 
+/* Similar to zmalloc, '*usable' is set to the usable size. */
+void *zmalloc_usable(size_t size, size_t *usable) {
+    void *ptr = malloc(size+PREFIX_SIZE);
+
+    if (!ptr) zmalloc_oom_handler(size);
+#ifdef HAVE_MALLOC_SIZE
+    update_zmalloc_stat_alloc(*usable = zmalloc_size(ptr));
+    return ptr;
+#else
+    *((size_t*)ptr) = *usable = size;
+    update_zmalloc_stat_alloc(size+PREFIX_SIZE);
+    return (char*)ptr+PREFIX_SIZE;
+#endif
+}
+
 /* Allocation and free functions that bypass the thread cache
  * and go straight to the allocator arena bins.
  * Currently implemented only for jemalloc. Used for online defragmentation. */
@@ -131,6 +146,21 @@ void *zcalloc(size_t size) {
 #endif
 }
 
+/* Similar to zcalloc, '*usable' is set to the usable size. */
+void *zcalloc_usable(size_t size, size_t *usable) {
+    void *ptr = calloc(1, size+PREFIX_SIZE);
+
+    if (!ptr) zmalloc_oom_handler(size);
+#ifdef HAVE_MALLOC_SIZE
+    update_zmalloc_stat_alloc(*usable = zmalloc_size(ptr));
+    return ptr;
+#else
+    *((size_t*)ptr) = *usable = size;
+    update_zmalloc_stat_alloc(size+PREFIX_SIZE);
+    return (char*)ptr+PREFIX_SIZE;
+#endif
+}
+
 void *zrealloc(void *ptr, size_t size) {
 #ifndef HAVE_MALLOC_SIZE
     void *realptr;
@@ -164,6 +194,41 @@ void *zrealloc(void *ptr, size_t size) {
 #endif
 }
 
+/* Similar to zrealloc, '*usable' is set to the new usable size. */
+void *zrealloc_usable(void *ptr, size_t size, size_t *usable) {
+#ifndef HAVE_MALLOC_SIZE
+    void *realptr;
+#endif
+    size_t oldsize;
+    void *newptr;
+
+    if (size == 0 && ptr != NULL) {
+        zfree(ptr);
+        *usable = 0;
+        return NULL;
+    }
+    if (ptr == NULL) return zmalloc_usable(size, usable);
+#ifdef HAVE_MALLOC_SIZE
+    oldsize = zmalloc_size(ptr);
+    newptr = realloc(ptr,size);
+    if (!newptr) zmalloc_oom_handler(size);
+
+    update_zmalloc_stat_free(oldsize);
+    update_zmalloc_stat_alloc(*usable = zmalloc_size(newptr));
+    return newptr;
+#else
+    realptr = (char*)ptr-PREFIX_SIZE;
+    oldsize = *((size_t*)realptr);
+    newptr = realloc(realptr,size+PREFIX_SIZE);
+    if (!newptr) zmalloc_oom_handler(size);
+
+    *((size_t*)newptr) = *usable = size;
+    update_zmalloc_stat_free(oldsize);
+    update_zmalloc_stat_alloc(size);
+    return (char*)newptr+PREFIX_SIZE;
+#endif
+}
+
 /* Provide zmalloc_size() for systems where this function is not provided by
  * malloc itself, given that in that case we store a header with this
  * information as the first bytes of every allocation. */
@@ -176,7 +241,7 @@ size_t zmalloc_size(void *ptr) {
     if (size&(sizeof(long)-1)) size += sizeof(long)-(size&(sizeof(long)-1));
     return size+PREFIX_SIZE;
 }
-size_t zmalloc_usable(void *ptr) {
+size_t zmalloc_usable_size(void *ptr) {
     return zmalloc_size(ptr)-PREFIX_SIZE;
 }
 #endif
@@ -199,6 +264,25 @@ void zfree(void *ptr) {
 #endif
 }
 
+/* Similar to zfree, '*usable' is set to the usable size being freed. */
+void zfree_usable(void *ptr, size_t *usable) {
+#ifndef HAVE_MALLOC_SIZE
+    void *realptr;
+    size_t oldsize;
+#endif
+
+    if (ptr == NULL) return;
+#ifdef HAVE_MALLOC_SIZE
+    update_zmalloc_stat_free(*usable = zmalloc_size(ptr));
+    free(ptr);
+#else
+    realptr = (char*)ptr-PREFIX_SIZE;
+    *usable = oldsize = *((size_t*)realptr);
+    update_zmalloc_stat_free(oldsize+PREFIX_SIZE);
+    free(realptr);
+#endif
+}
+
 char *zstrdup(const char *s) {
     size_t l = strlen(s)+1;
     char *p = zmalloc(l);

src/zmalloc.h

@@ -81,6 +81,10 @@ void *zmalloc(size_t size);
 void *zcalloc(size_t size);
 void *zrealloc(void *ptr, size_t size);
 void zfree(void *ptr);
+void *zmalloc_usable(size_t size, size_t *usable);
+void *zcalloc_usable(size_t size, size_t *usable);
+void *zrealloc_usable(void *ptr, size_t size, size_t *usable);
+void zfree_usable(void *ptr, size_t *usable);
 char *zstrdup(const char *s);
 size_t zmalloc_used_memory(void);
 void zmalloc_set_oom_handler(void (*oom_handler)(size_t));
@@ -100,9 +104,9 @@ void *zmalloc_no_tcache(size_t size);
 
 #ifndef HAVE_MALLOC_SIZE
 size_t zmalloc_size(void *ptr);
-size_t zmalloc_usable(void *ptr);
+size_t zmalloc_usable_size(void *ptr);
 #else
-#define zmalloc_usable(p) zmalloc_size(p)
+#define zmalloc_usable_size(p) zmalloc_size(p)
 #endif
 
 #ifdef REDIS_TEST