Merge pull request #6531 from oranagra/rm_save_long_double

Module API for loading and saving long double

src/module.c

@@ -3769,6 +3769,31 @@ loaderr:
     return 0;
 }
 
+/* In the context of the rdb_save method of a module data type, saves a long double
+ * value to the RDB file. The double can be a valid number, a NaN or infinity.
+ * It is possible to load back the value with RedisModule_LoadLongDouble(). */
+void RM_SaveLongDouble(RedisModuleIO *io, long double value) {
+    if (io->error) return;
+    char buf[MAX_LONG_DOUBLE_CHARS];
+    /* Long double has different number of bits in different platforms, so we
+     * save it as a string type. */
+    size_t len = ld2string(buf,sizeof(buf),value,LD_STR_HEX);
+    RM_SaveStringBuffer(io,buf,len+1); /* len+1 for '\0' */
+}
+
+/* In the context of the rdb_save method of a module data type, loads back the
+ * long double value saved by RedisModule_SaveLongDouble(). */
+long double RM_LoadLongDouble(RedisModuleIO *io) {
+    if (io->error) return 0;
+    long double value;
+    size_t len;
+    char* str = RM_LoadStringBuffer(io,&len);
+    if (!str) return 0;
+    string2ld(str,len,&value);
+    RM_Free(str);
+    return value;
+}
+
 /* Iterate over modules, and trigger rdb aux saving for the ones modules types
  * who asked for it. */
 ssize_t rdbSaveModulesAux(rio *rdb, int when) {
@@ -6849,6 +6874,8 @@ void moduleRegisterCoreAPI(void) {
     REGISTER_API(LoadDouble);
     REGISTER_API(SaveFloat);
     REGISTER_API(LoadFloat);
+    REGISTER_API(SaveLongDouble);
+    REGISTER_API(LoadLongDouble);
     REGISTER_API(EmitAOF);
     REGISTER_API(Log);
     REGISTER_API(LogIOError);

src/networking.c

@@ -530,7 +530,7 @@ void addReplyHumanLongDouble(client *c, long double d) {
         decrRefCount(o);
     } else {
         char buf[MAX_LONG_DOUBLE_CHARS];
-        int len = ld2string(buf,sizeof(buf),d,1);
+        int len = ld2string(buf,sizeof(buf),d,LD_STR_HUMAN);
         addReplyProto(c,",",1);
         addReplyProto(c,buf,len);
         addReplyProto(c,"\r\n",2);

src/object.c

@@ -178,7 +178,7 @@ robj *createStringObjectFromLongLongForValue(long long value) {
  * The 'humanfriendly' option is used for INCRBYFLOAT and HINCRBYFLOAT. */
 robj *createStringObjectFromLongDouble(long double value, int humanfriendly) {
     char buf[MAX_LONG_DOUBLE_CHARS];
-    int len = ld2string(buf,sizeof(buf),value,humanfriendly);
+    int len = ld2string(buf,sizeof(buf),value,humanfriendly? LD_STR_HUMAN: LD_STR_AUTO);
     return createStringObject(buf,len);
 }
 

src/redismodule.h

@@ -535,6 +535,8 @@ void REDISMODULE_API_FUNC(RedisModule_SaveDouble)(RedisModuleIO *io, double valu
 double REDISMODULE_API_FUNC(RedisModule_LoadDouble)(RedisModuleIO *io);
 void REDISMODULE_API_FUNC(RedisModule_SaveFloat)(RedisModuleIO *io, float value);
 float REDISMODULE_API_FUNC(RedisModule_LoadFloat)(RedisModuleIO *io);
+void REDISMODULE_API_FUNC(RedisModule_SaveLongDouble)(RedisModuleIO *io, long double value);
+long double REDISMODULE_API_FUNC(RedisModule_LoadLongDouble)(RedisModuleIO *io);
 void REDISMODULE_API_FUNC(RedisModule_Log)(RedisModuleCtx *ctx, const char *level, const char *fmt, ...);
 void REDISMODULE_API_FUNC(RedisModule_LogIOError)(RedisModuleIO *io, const char *levelstr, const char *fmt, ...);
 void REDISMODULE_API_FUNC(RedisModule__Assert)(const char *estr, const char *file, int line);
@@ -741,6 +743,8 @@ static int RedisModule_Init(RedisModuleCtx *ctx, const char *name, int ver, int
     REDISMODULE_GET_API(LoadDouble);
     REDISMODULE_GET_API(SaveFloat);
     REDISMODULE_GET_API(LoadFloat);
+    REDISMODULE_GET_API(SaveLongDouble);
+    REDISMODULE_GET_API(LoadLongDouble);
     REDISMODULE_GET_API(EmitAOF);
     REDISMODULE_GET_API(Log);
     REDISMODULE_GET_API(LogIOError);

src/t_hash.c

@@ -621,7 +621,7 @@ void hincrbyfloatCommand(client *c) {
     }
 
     char buf[MAX_LONG_DOUBLE_CHARS];
-    int len = ld2string(buf,sizeof(buf),value,1);
+    int len = ld2string(buf,sizeof(buf),value,LD_STR_HUMAN);
     new = sdsnewlen(buf,len);
     hashTypeSet(o,c->argv[2]->ptr,new,HASH_SET_TAKE_VALUE);
     addReplyBulkCBuffer(c,buf,len);

src/util.c

@@ -510,15 +510,17 @@ int d2string(char *buf, size_t len, double value) {
     return len;
 }
 
-/* Convert a long double into a string. If humanfriendly is non-zero
- * it does not use exponential format and trims trailing zeroes at the end,
- * however this results in loss of precision. Otherwise exp format is used
- * and the output of snprintf() is not modified.
+/* Create a string object from a long double.
+ * If mode is humanfriendly it does not use exponential format and trims trailing
+ * zeroes at the end (may result in loss of precision).
+ * If mode is default exp format is used and the output of snprintf()
+ * is not modified (may result in loss of precision).
+ * If mode is hex hexadecimal format is used (no loss of precision)
  *
  * The function returns the length of the string or zero if there was not
  * enough buffer room to store it. */
-int ld2string(char *buf, size_t len, long double value, int humanfriendly) {
-    size_t l;
+int ld2string(char *buf, size_t len, long double value, ld2string_mode mode) {
+    size_t l = 0;
 
     if (isinf(value)) {
         /* Libc in odd systems (Hi Solaris!) will format infinite in a
@@ -531,26 +533,36 @@ int ld2string(char *buf, size_t len, long double value, int humanfriendly) {
             memcpy(buf,"-inf",4);
             l = 4;
         }
-    } else if (humanfriendly) {
-        /* We use 17 digits precision since with 128 bit floats that precision
-         * after rounding is able to represent most small decimal numbers in a
-         * way that is "non surprising" for the user (that is, most small
-         * decimal numbers will be represented in a way that when converted
-         * back into a string are exactly the same as what the user typed.) */
-        l = snprintf(buf,len,"%.17Lf", value);
-        if (l+1 > len) return 0; /* No room. */
-        /* Now remove trailing zeroes after the '.' */
-        if (strchr(buf,'.') != NULL) {
-            char *p = buf+l-1;
-            while(*p == '0') {
-                p--;
-                l--;
-            }
-            if (*p == '.') l--;
-        }
     } else {
-        l = snprintf(buf,len,"%.17Lg", value);
-        if (l+1 > len) return 0; /* No room. */
+        switch (mode) {
+        case LD_STR_AUTO:
+            l = snprintf(buf,len,"%.17Lg",value);
+            if (l+1 > len) return 0; /* No room. */
+            break;
+        case LD_STR_HEX:
+            l = snprintf(buf,len,"%La",value);
+            if (l+1 > len) return 0; /* No room. */
+            break;
+        case LD_STR_HUMAN:
+            /* We use 17 digits precision since with 128 bit floats that precision
+             * after rounding is able to represent most small decimal numbers in a
+             * way that is "non surprising" for the user (that is, most small
+             * decimal numbers will be represented in a way that when converted
+             * back into a string are exactly the same as what the user typed.) */
+            l = snprintf(buf,len,"%.17Lf",value);
+            if (l+1 > len) return 0; /* No room. */
+            /* Now remove trailing zeroes after the '.' */
+            if (strchr(buf,'.') != NULL) {
+                char *p = buf+l-1;
+                while(*p == '0') {
+                    p--;
+                    l--;
+                }
+                if (*p == '.') l--;
+            }
+            break;
+        default: return 0; /* Invalid mode. */
+        }
     }
     buf[l] = '\0';
     return l;

src/util.h

@@ -38,6 +38,13 @@
  * This should be the size of the buffer given to ld2string */
 #define MAX_LONG_DOUBLE_CHARS 5*1024
 
+/* long double to string convertion options */
+typedef enum {
+    LD_STR_AUTO,     /* %.17Lg */
+    LD_STR_HUMAN,    /* %.17Lf + Trimming of trailing zeros */
+    LD_STR_HEX       /* %La */
+} ld2string_mode;
+
 int stringmatchlen(const char *p, int plen, const char *s, int slen, int nocase);
 int stringmatch(const char *p, const char *s, int nocase);
 int stringmatchlen_fuzz_test(void);
@@ -49,7 +56,7 @@ int string2ll(const char *s, size_t slen, long long *value);
 int string2l(const char *s, size_t slen, long *value);
 int string2ld(const char *s, size_t slen, long double *dp);
 int d2string(char *buf, size_t len, double value);
-int ld2string(char *buf, size_t len, long double value, int humanfriendly);
+int ld2string(char *buf, size_t len, long double value, ld2string_mode mode);
 sds getAbsolutePath(char *filename);
 unsigned long getTimeZone(void);
 int pathIsBaseName(char *path);

tests/modules/testrdb.c

@@ -15,11 +15,16 @@ RedisModuleString *after_str = NULL;
 
 void *testrdb_type_load(RedisModuleIO *rdb, int encver) {
     int count = RedisModule_LoadSigned(rdb);
+    RedisModuleString *str = RedisModule_LoadString(rdb);
+    float f = RedisModule_LoadFloat(rdb);
+    long double ld = RedisModule_LoadLongDouble(rdb);
     if (RedisModule_IsIOError(rdb))
         return NULL;
+    /* Using the values only after checking for io errors. */
     assert(count==1);
     assert(encver==1);
-    RedisModuleString *str = RedisModule_LoadString(rdb);
+    assert(f==1.5f);
+    assert(ld==0.333333333333333333L);
     return str;
 }
 
@@ -27,6 +32,8 @@ void testrdb_type_save(RedisModuleIO *rdb, void *value) {
     RedisModuleString *str = (RedisModuleString*)value;
     RedisModule_SaveSigned(rdb, 1);
     RedisModule_SaveString(rdb, str);
+    RedisModule_SaveFloat(rdb, 1.5);
+    RedisModule_SaveLongDouble(rdb, 0.333333333333333333L);
 }
 
 void testrdb_aux_save(RedisModuleIO *rdb, int when) {