* Add length param for seralization write_string

to increase a little bit the performance for big strings.
* Change the format of storing strings for serial-bin.

README.md

@@ -5869,7 +5869,7 @@ the following fields with the following definition:
    Write the float 'data' of 'size_of_type' bytes into the serial stream 'serial'.
    Return M\_SERIAL\_OK\_DONE if it succeeds, M\_SERIAL\_FAIL otherwise */
 * write\_string:
-   Write the null-terminated string 'data'into the serial stream 'serial'.
+   Write the null-terminated string 'data' of 'length' characters into the serial stream 'serial'.
    Return M\_SERIAL\_OK\_DONE if it succeeds, M\_SERIAL\_FAIL otherwise */
 * write\_array\_start:
    Start writing an array of 'number_of_elements' objects into the serial stream 'serial'.
@@ -5981,7 +5981,7 @@ The full C definition are:
           m_serial_return_code_t (*write_boolean)(m_serial_write_t serial, const bool b);
           m_serial_return_code_t (*write_integer)(m_serial_write_t serial, const long long i, const size_t size_of_type);
           m_serial_return_code_t (*write_float)(m_serial_write_t serial,  const long double f, const size_t size_of_type);
-          m_serial_return_code_t (*write_string)(m_serial_write_t serial, const char s[]); 
+          m_serial_return_code_t (*write_string)(m_serial_write_t serial, const char s[], size_t length); 
           m_serial_return_code_t (*write_array_start)(m_serial_local_t local, m_serial_write_t serial, const size_t number_of_elements);
           m_serial_return_code_t (*write_array_next)(m_serial_local_t local, m_serial_write_t serial);
           m_serial_return_code_t (*write_array_end)(m_serial_local_t local, m_serial_write_t serial);

doc/API.txt

@@ -50,4 +50,4 @@ V0.4.*: * The order of a list initialized using M_LET is reversed
         to match what is done for ARRAY (and the C++ forward_list).
         * Rename M_SKIP, M_KEEP & M_MID into M_SKIP_ARGS, M_KEEP_ARGS & M_MID_ARGS
         due to conflict with glibc malloc.h (that defines M_KEEP for compatibility).
-        
+        * Method write_string of m_serial expects a new argument (number of characters)

m-core.h

@@ -2995,7 +2995,7 @@ typedef struct m_serial_write_interface_s {
   m_serial_return_code_t (*write_boolean)(m_serial_write_t,const bool data);
   m_serial_return_code_t (*write_integer)(m_serial_write_t,const long long data, const size_t size_of_type);
   m_serial_return_code_t (*write_float)(m_serial_write_t, const long double data, const size_t size_of_type);
-  m_serial_return_code_t (*write_string)(m_serial_write_t,const char data[]); 
+  m_serial_return_code_t (*write_string)(m_serial_write_t,const char data[], size_t len); 
   m_serial_return_code_t (*write_array_start)(m_serial_local_t, m_serial_write_t, const size_t number_of_elements);
   m_serial_return_code_t (*write_array_next)(m_serial_local_t, m_serial_write_t);
   m_serial_return_code_t (*write_array_end)(m_serial_local_t, m_serial_write_t);
@@ -3031,8 +3031,8 @@ typedef struct m_serial_write_interface_s {
            float: (serial)->m_interface->write_float(serial, M_AS_TYPE(float,(x)), sizeof (x)), \
            double: (serial)->m_interface->write_float(serial, M_AS_TYPE(double,(x)), sizeof (x)), \
            long double: (serial)->m_interface->write_float(serial, M_AS_TYPE(long double,(x)), sizeof (x)), \
-           const char *: (serial)->m_interface->write_string(serial, M_AS_TYPE(const char *,(x))), \
-           char *: (serial)->m_interface->write_string(serial, M_AS_TYPE(char *,(x))), \
+           const char *: (serial)->m_interface->write_string(serial, M_AS_TYPE(const char *,(x)), m_core_out_serial_strlen(M_AS_TYPE(const char *,(x))) ), \
+           char *: (serial)->m_interface->write_string(serial, M_AS_TYPE(char *,(x)), m_core_out_serial_strlen(M_AS_TYPE(const char *,(x))) ), \
            const void *: M_SERIAL_FAIL /* unsupported */,               \
            void *: M_SERIAL_FAIL /* unsupported */)
 
@@ -3089,4 +3089,15 @@ M_IN_SERIAL_DEFAULT_TYPE_DEF(m_core_in_serial_float, float, read_float, long dou
 M_IN_SERIAL_DEFAULT_TYPE_DEF(m_core_in_serial_double, double, read_float, long double)
 M_IN_SERIAL_DEFAULT_TYPE_DEF(m_core_in_serial_ldouble, long double, read_float, long double)
 
+/* Encapsulation of strlen to avoid warnings in M_OUT_SERIAL_DEFAULT_ARG
+ * because of expanded code will call strlen with NULL (which is illegal)
+ * However, the branch where it is called is unreachable, so the warning
+ * is not justified. */
+static size_t
+m_core_out_serial_strlen(const char s[])
+{
+  assert(s != NULL);
+  return strlen(s);
+}
+
 #endif

m-serial-bin.h

@@ -30,6 +30,66 @@
 #include "m-core.h"
 #include "m-string.h"
 
+/* Internal service:
+ * Write size_t in the stream in a compact form to reduce consumption
+ * (and I/O bandwidth)
+ */
+static inline bool
+m_serial_bin_write_size(FILE *f, const size_t size)
+{
+  bool b;
+  if (M_LIKELY(size < 253))
+  {
+    b = EOF != fputc((unsigned char) size, f);
+  } else if (size < 1ULL << 16) {
+    b = EOF != fputc(253, f);    // Save 16 bits encoding
+    b &= EOF != fputc((unsigned char) (size >> 8), f);
+    b &= EOF != fputc((unsigned char) size, f);
+  } else if (size < 1ULL<< 32) {
+    b = EOF != fputc(254, f);    // Save 32 bits encoding
+    b &= EOF != fputc((unsigned char) (size >> 24), f);
+    b &= EOF != fputc((unsigned char) (size >> 16), f);
+    b &= EOF != fputc((unsigned char) (size >> 8), f);
+    b &= EOF != fputc((unsigned char) size, f);
+  } else {
+    b = EOF != fputc(255, f);    // Save 64 bits encoding
+    b &= EOF != fputc((unsigned char) (size >> 56), f);
+    b &= EOF != fputc((unsigned char) (size >> 48), f);
+    b &= EOF != fputc((unsigned char) (size >> 40), f);
+    b &= EOF != fputc((unsigned char) (size >> 32), f);
+    b &= EOF != fputc((unsigned char) (size >> 24), f);
+    b &= EOF != fputc((unsigned char) (size >> 16), f);
+    b &= EOF != fputc((unsigned char) (size >> 8), f);
+    b &= EOF != fputc((unsigned char) size, f);
+  }
+  return b;
+}
+
+/* Internal service:
+ * Read size_t in the stream from a compact form to reduce consumption
+ * (and I/O bandwidth)
+ */
+static inline bool
+m_serial_bin_read_size(FILE *f, size_t *size)
+{
+  int c;
+  c = fgetc(f);
+  if (M_UNLIKELY(c == EOF)) return false;
+  if (M_LIKELY(c < 253)) {
+    *size = (size_t) c;
+    return true;
+  }
+  size_t s = 0;
+  int l = (c = 255) ? 8 : (c == 254) ? 4 : 2;
+  for(int i = 0; i < l; i++) {
+      c = fgetc(f);
+      if (M_UNLIKELY(c == EOF)) return false;
+      s = (s << 8) | (size_t) c;
+  }
+  *size = s;
+  return true;
+}
+
 /* Write the boolean 'data' into the serial stream 'serial'.
    Return M_SERIAL_OK_DONE if it succeeds, M_SERIAL_FAIL otherwise */
 static inline m_serial_return_code_t
@@ -105,12 +165,17 @@ m_serial_bin_write_float(m_serial_write_t serial, const long double data, const
 /* Write the null-terminated string 'data'into the serial stream 'serial'.
    Return M_SERIAL_OK_DONE if it succeeds, M_SERIAL_FAIL otherwise */
 static inline m_serial_return_code_t
-m_serial_bin_write_string(m_serial_write_t serial, const char data[])
+m_serial_bin_write_string(m_serial_write_t serial, const char data[], size_t length)
 {
+  STRINGI_ASSUME(length == strlen(data) );
   FILE *f = (FILE *)serial->data[0].p;
-  size_t l = strlen(data);
-  size_t n = fwrite (M_ASSIGN_CAST(const void*, data), 1, l+1, f);
-  return n == l+1 ? M_SERIAL_OK_DONE : M_SERIAL_FAIL;
+  assert(f != NULL && data != NULL);
+  // Write first the number of (non null) characters
+  if (m_serial_bin_write_size(f, length) != true) return M_SERIAL_FAIL;
+  // Write the characters (excluding the final null char)
+  // NOTE: fwrite supports length == 0.
+  size_t n = fwrite (M_ASSIGN_CAST(const void*, data), 1, length, f);
+  return (n == length) ? M_SERIAL_OK_DONE : M_SERIAL_FAIL;
 }
 
 /* Start writing an array of 'number_of_elements' objects into the serial stream 'serial'.
@@ -345,14 +410,20 @@ m_serial_bin_read_float(m_serial_read_t serial, long double *r, const size_t siz
 static inline  m_serial_return_code_t
 m_serial_bin_read_string(m_serial_read_t serial, struct string_s *s){
   FILE *f = (FILE*) serial->data[0].p;
-  string_clean(s);
-  int c;
-  c = fgetc(f);
-  while (c != 0 && c != EOF) {
-    string_push_back(s, c);
-    c = fgetc(f);
-  }
-  return c != EOF ? M_SERIAL_OK_DONE : M_SERIAL_FAIL;
+  assert(f != NULL && s != NULL);
+  // First read the number of non null characters
+  size_t length;
+  if (m_serial_bin_read_size(f, &length) != true) return M_SERIAL_FAIL;
+  // Use of internal string interface to dimension the string
+  string_reserve(s, length + 1);
+  char *p = stringi_get_str(s);
+  stringi_set_size(s, length);
+  // Read the characters excluding the final null one.
+  // NOTE: fread supports length == 0.
+  size_t n = fread(M_ASSIGN_CAST(void*, p), 1, length, f);
+  // Force the final null character
+  p[length] = 0;
+  return (n == length) ? M_SERIAL_OK_DONE : M_SERIAL_FAIL;
 }
 
 /* Start reading from the stream 'serial' an array.

m-serial-json.h

@@ -63,14 +63,16 @@ m_serial_json_write_float(m_serial_write_t serial, const long double data, const
 /* Write the null-terminated string 'data'into the serial stream 'serial'.
    Return M_SERIAL_OK_DONE if it succeeds, M_SERIAL_FAIL otherwise */
 static inline m_serial_return_code_t
-m_serial_json_write_string(m_serial_write_t serial, const char data[])
+m_serial_json_write_string(m_serial_write_t serial, const char data[], size_t length)
 {
+  STRINGI_ASSUME(length == strlen(data) );
   FILE *f = (FILE *)serial->data[0].p;
-  /* Build dummy string to reuse string_out_str */
+  assert(f != NULL && data != NULL);
+  /* HACK: Build dummy string to reuse string_out_str */
   string_t v2;
   uintptr_t ptr = (uintptr_t) data;
-  v2->u.heap.size = strlen(data);
-  v2->u.heap.alloc = v2->u.heap.size + 1;
+  v2->u.heap.size = length;
+  v2->u.heap.alloc = length + 1;
   v2->ptr = (char*)ptr;
   string_out_str(f, v2);
   return M_SERIAL_OK_DONE;

m-string.h

@@ -1241,7 +1241,7 @@ static inline m_serial_return_code_t
 string_out_serial(m_serial_write_t serial, const string_t v)
 {
   assert (serial != NULL && serial->m_interface != NULL);
-  return serial->m_interface->write_string(serial, string_get_cstr(v));
+  return serial->m_interface->write_string(serial, string_get_cstr(v), string_size(v) );
 }
 
 /* Read the formatted string from the serializer
@@ -2047,7 +2047,7 @@ namespace m_string {
   {                                                                     \
     BOUNDED_STRINGI_CONTRACT(v, max_size);                              \
     assert (serial != NULL && serial->m_interface != NULL);             \
-    return serial->m_interface->write_string(serial, v->s);             \
+    return serial->m_interface->write_string(serial, v->s, strlen(v->s) ); \
   }                                                                     \
                                                                         \
   static inline m_serial_return_code_t                                  \