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BSON_API(3) Libbson BSON_API(3)

NAME

bson_api - API Reference

BSON_T

BSON Document Abstraction

Synopsis

#include <bson.h>
BSON_ALIGNED_BEGIN (128)
typedef struct {
   uint32_t flags;       /* Internal flags for the bson_t. */
   uint32_t len;         /* Length of BSON data. */
   uint8_t padding[120]; /* Padding for stack allocation. */
} bson_t BSON_ALIGNED_END (128);


Description

The bson_t structure represents a BSON document. This structure manages the underlying BSON encoded buffer. For mutable documents, it can append new data to the document.

Performance Notes

The bson_t structure attempts to use an inline allocation within the structure to speed up performance of small documents. When this internal buffer has been exhausted, a heap allocated buffer will be dynamically allocated. Therefore, it is essential to call bson_destroy() on allocated documents.

Example

static void
create_on_heap (void)
{
   bson_t *b = bson_new ();
   BSON_APPEND_INT32 (b, "foo", 123);
   BSON_APPEND_UTF8 (b, "bar", "foo");
   BSON_APPEND_DOUBLE (b, "baz", 1.23f);
   bson_destroy (b);
}


BSON_CONTEXT_T

BSON OID Generation Context

Synopsis

#include <bson.h>
typedef enum {
   BSON_CONTEXT_NONE = 0,
   BSON_CONTEXT_THREAD_SAFE = (1 << 0),
   BSON_CONTEXT_DISABLE_HOST_CACHE = (1 << 1),
   BSON_CONTEXT_DISABLE_PID_CACHE = (1 << 2),
#ifdef BSON_HAVE_SYSCALL_TID
   BSON_CONTEXT_USE_TASK_ID = (1 << 3),
#endif
} bson_context_flags_t;
typedef struct _bson_context_t bson_context_t;
bson_context_t *
bson_context_get_default (void) BSON_GNUC_CONST;
bson_context_t *
bson_context_new (bson_context_flags_t flags);
void
bson_context_destroy (bson_context_t *context);


Description

The bson_context_t structure is context for generation of BSON Object IDs. This context allows for specialized overriding of how ObjectIDs are generated based on the applications requirements. For example, disabling of PID caching can be configured if the application cannot detect when a call to fork() has occurred.

Example

#include <bson.h>
int
main (int argc, char *argv[])
{
   bson_context_t *ctx = NULL;
   bson_oid_t oid;
   /* use default context, via bson_context_get_default() */
   bson_oid_init (&oid, NULL);
   /* specify a local context for additional control */
   ctx = bson_context_new (BSON_CONTEXT_DISABLE_PID_CACHE |
                           BSON_CONTEXT_THREAD_SAFE);
   bson_oid_init (&oid, ctx);
   bson_context_destroy (ctx);
   return 0;
}


BSON_DECIMAL128_T

BSON Decimal128 Abstraction

Synopsis

#include <bson.h>
typedef struct {
#if BSON_BYTE_ORDER == BSON_LITTLE_ENDIAN
   uint64_t low;
   uint64_t high;
#elif BSON_BYTE_ORDER == BSON_BIG_ENDIAN
   uint64_t high;
   uint64_t low;
#endif
} bson_decimal128_t;


Description

The bson_decimal128_t structure represents the IEEE-754 Decimal128 data type.

Example

#include <bson.h>
#include <stdio.h>
int
main (int argc, char *argv[])
{
   char string[BSON_DECIMAL128_STRING];
   bson_decimal128_t decimal128;
   bson_decimal128_from_string ("100.00", &decimal128);
   bson_decimal128_to_string (&decimal128, string);
   printf ("Decimal128 value: %s\n", string);
   return 0;
}


BSON_ERROR_T

BSON Error Encapsulation

Synopsis

#include <bson.h>
typedef struct {
   uint32_t domain;
   uint32_t code;
   char message[504];
} bson_error_t;


Description

The bson_error_t structure is used as an out-parameter to pass error information to the caller. It should be stack-allocated and does not requiring freeing.

See Handling Errors.

Example

bson_reader_t *reader;
bson_error_t error;
reader = bson_reader_new_from_file ("dump.bson", &error);
if (!reader) {
   fprintf (
      stderr, "ERROR: %d.%d: %s\n", error.domain, error.code, error.message);
}


BSON_ITER_T

BSON Document Iterator

Synopsis

#include <bson.h>
typedef struct {
   /*< private >*/
} bson_iter_t;


Description

bson_iter_t is a structure used to iterate through the elements of a bson_t. It is meant to be used on the stack and can be discarded at any time as it contains no external allocation. The contents of the structure should be considered private and may change between releases, however the structure size will not change.

The bson_t MUST be valid for the lifetime of the iter and it is an error to modify the bson_t while using the iter.

Examples

bson_iter_t iter;
if (bson_iter_init (&iter, my_bson_doc)) {
   while (bson_iter_next (&iter)) {
      printf ("Found a field named: %s\n", bson_iter_key (&iter));
   }
}


bson_iter_t iter;
if (bson_iter_init (&iter, my_bson_doc) && bson_iter_find (&iter, "my_field")) {
   printf ("Found the field named: %s\n", bson_iter_key (&iter));
}


bson_iter_t iter;
bson_iter_t sub_iter;
if (bson_iter_init_find (&iter, my_bson_doc, "mysubdoc") &&
    (BSON_ITER_HOLDS_DOCUMENT (&iter) || BSON_ITER_HOLDS_ARRAY (&iter)) &&
    bson_iter_recurse (&iter, &sub_iter)) {
   while (bson_iter_next (&sub_iter)) {
      printf ("Found key \"%s\" in sub document.\n", bson_iter_key (&sub_iter));
   }
}


bson_iter_t iter;
if (bson_iter_init (&iter, my_doc) &&
    bson_iter_find_descendant (&iter, "a.b.c.d", &sub_iter)) {
   printf ("The type of a.b.c.d is: %d\n", (int) bson_iter_type (&sub_iter));
}


BSON_JSON_READER_T

Bulk JSON to BSON conversion

Synopsis

#include <bson.h>
typedef struct _bson_json_reader_t bson_json_reader_t;
typedef enum {
   BSON_JSON_ERROR_READ_CORRUPT_JS = 1,
   BSON_JSON_ERROR_READ_INVALID_PARAM,
   BSON_JSON_ERROR_READ_CB_FAILURE,
} bson_json_error_code_t;


Description

The bson_json_reader_t structure is used for reading a sequence of JSON documents and transforming them to bson_t documents.

This can often be useful if you want to perform bulk operations that are defined in a file containing JSON documents.

Example

/*
 * Copyright 2013 MongoDB, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * This program will print each JSON document contained in the provided files
 * as a BSON string to STDOUT.
 */
#include <bson.h>
#include <stdlib.h>
#include <stdio.h>
int
main (int argc, char *argv[])
{
   bson_json_reader_t *reader;
   bson_error_t error;
   const char *filename;
   bson_t doc = BSON_INITIALIZER;
   int i;
   int b;
   /*
    * Print program usage if no arguments are provided.
    */
   if (argc == 1) {
      fprintf (stderr, "usage: %s FILE...\n", argv[0]);
      return 1;
   }
   /*
    * Process command line arguments expecting each to be a filename.
    */
   for (i = 1; i < argc; i++) {
      filename = argv[i];
      /*
       * Open the filename provided in command line arguments.
       */
      if (0 == strcmp (filename, "-")) {
         reader = bson_json_reader_new_from_fd (STDIN_FILENO, false);
      } else {
         if (!(reader = bson_json_reader_new_from_file (filename, &error))) {
            fprintf (
               stderr, "Failed to open \"%s\": %s\n", filename, error.message);
            continue;
         }
      }
      /*
       * Convert each incoming document to BSON and print to stdout.
       */
      while ((b = bson_json_reader_read (reader, &doc, &error))) {
         if (b < 0) {
            fprintf (stderr, "Error in json parsing:\n%s\n", error.message);
            abort ();
         }
         if (fwrite (bson_get_data (&doc), 1, doc.len, stdout) != doc.len) {
            fprintf (stderr, "Failed to write to stdout, exiting.\n");
            exit (1);
         }
         bson_reinit (&doc);
      }
      bson_json_reader_destroy (reader);
      bson_destroy (&doc);
   }
   return 0;
}


BSON_MD5_T

BSON MD5 Abstraction

Synopsis

typedef struct {
   uint32_t count[2]; /* message length in bits, lsw first */
   uint32_t abcd[4];  /* digest buffer */
   uint8_t buf[64];   /* accumulate block */
} bson_md5_t;


Description

bson_md5_t encapsulates an implementation of the MD5 algorithm. This is used in OID generation for the MD5(hostname) bytes. It is also used by some libraries such as the MongoDB C driver.

BSON_OID_T

BSON ObjectID Abstraction

Synopsis

#include <bson.h>
typedef struct {
   uint8_t bytes[12];
} bson_oid_t;


Description

The bson_oid_t structure contains the 12-byte ObjectId notation defined by the BSON ObjectID specification.

ObjectId is a 12-byte BSON type, constructed using:

  • a 4-byte value representing the seconds since the Unix epoch (in Big Endian)
  • a 3-byte machine identifier
  • a 2-byte process id (Big Endian), and
  • a 3-byte counter (Big Endian), starting with a random value.

String Conversion

You can convert an Object ID to a string using bson_oid_to_string() and back with bson_oid_init_from_string().

Hashing

A bson_oid_t can be used in hashtables using the function bson_oid_hash() and bson_oid_equal().

Comparing

A bson_oid_t can be compared to another using bson_oid_compare() for qsort() style comparing and bson_oid_equal() for direct equality.

Validating

You can validate that a string containing a hex-encoded ObjectID is valid using the function bson_oid_is_valid().

Example

#include <bson.h>
#include <stdio.h>
int
main (int argc, char *argv[])
{
   bson_oid_t oid;
   char str[25];
   bson_oid_init (&oid, NULL);
   bson_oid_to_string (&oid, str);
   printf ("%s\n", str);
   if (bson_oid_is_valid (str, sizeof str)) {
      bson_oid_init_from_string (&oid, str);
   }
   printf ("The UNIX time was: %u\n", (unsigned) bson_oid_get_time_t (&oid));
   return 0;
}


BSON_READER_T

Streaming BSON Document Reader

Synopsis

#include <bson.h>
typedef struct _bson_reader_t bson_reader_t;
bson_reader_t *
bson_reader_new_from_handle (void *handle,
                             bson_reader_read_func_t rf,
                             bson_reader_destroy_func_t df);
bson_reader_t *
bson_reader_new_from_fd (int fd, bool close_on_destroy);
bson_reader_t *
bson_reader_new_from_file (const char *path, bson_error_t *error);
bson_reader_t *
bson_reader_new_from_data (const uint8_t *data, size_t length);
void
bson_reader_destroy (bson_reader_t *reader);


Description

bson_reader_t is a structure used for reading a sequence of BSON documents. The sequence can come from a file-descriptor, memory region, or custom callbacks.

Example

/*
 * Copyright 2013 MongoDB, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * This program will print each BSON document contained in the provided files
 * as a JSON string to STDOUT.
 */
#include <bson.h>
#include <stdio.h>
int
main (int argc, char *argv[])
{
   bson_reader_t *reader;
   const bson_t *b;
   bson_error_t error;
   const char *filename;
   char *str;
   int i;
   /*
    * Print program usage if no arguments are provided.
    */
   if (argc == 1) {
      fprintf (stderr, "usage: %s [FILE | -]...\nUse - for STDIN.\n", argv[0]);
      return 1;
   }
   /*
    * Process command line arguments expecting each to be a filename.
    */
   for (i = 1; i < argc; i++) {
      filename = argv[i];
      if (strcmp (filename, "-") == 0) {
         reader = bson_reader_new_from_fd (STDIN_FILENO, false);
      } else {
         if (!(reader = bson_reader_new_from_file (filename, &error))) {
            fprintf (
               stderr, "Failed to open \"%s\": %s\n", filename, error.message);
            continue;
         }
      }
      /*
       * Convert each incoming document to JSON and print to stdout.
       */
      while ((b = bson_reader_read (reader, NULL))) {
         str = bson_as_json (b, NULL);
         fprintf (stdout, "%s\n", str);
         bson_free (str);
      }
      /*
       * Cleanup after our reader, which closes the file descriptor.
       */
      bson_reader_destroy (reader);
   }
   return 0;
}


BSON_STRING_T

String Building Abstraction

Synopsis

#include <bson.h>
typedef struct {
   char *str;
   uint32_t len;
   uint32_t alloc;
} bson_string_t;


Description

bson_string_t is an abstraction for building strings. As chunks are added to the string, allocations are performed in powers of two.

This API is useful if you need to build UTF-8 encoded strings.

Example

bson_string_t *str;
str = bson_string_new (NULL);
bson_string_append_printf (str, "%d %s %f\n", 0, "some string", 0.123);
printf ("%s\n", str->str);
bson_string_free (str, true);


BSON_SUBTYPE_T

Binary Field Subtype

Synopsis

#include <bson.h>
typedef enum {
   BSON_SUBTYPE_BINARY = 0x00,
   BSON_SUBTYPE_FUNCTION = 0x01,
   BSON_SUBTYPE_BINARY_DEPRECATED = 0x02,
   BSON_SUBTYPE_UUID_DEPRECATED = 0x03,
   BSON_SUBTYPE_UUID = 0x04,
   BSON_SUBTYPE_MD5 = 0x05,
   BSON_SUBTYPE_USER = 0x80,
} bson_subtype_t;


Description

This enumeration contains the various subtypes that may be used in a binary field. See http://bsonspec.org for more information.

Example

bson_t doc = BSON_INITIALIZER;
BSON_APPEND_BINARY (&doc, "binary", BSON_SUBTYPE_BINARY, data, data_len);


BSON_TYPE_T

BSON Type Enumeration

Synopsis

#include <bson.h>
typedef enum {
   BSON_TYPE_EOD = 0x00,
   BSON_TYPE_DOUBLE = 0x01,
   BSON_TYPE_UTF8 = 0x02,
   BSON_TYPE_DOCUMENT = 0x03,
   BSON_TYPE_ARRAY = 0x04,
   BSON_TYPE_BINARY = 0x05,
   BSON_TYPE_UNDEFINED = 0x06,
   BSON_TYPE_OID = 0x07,
   BSON_TYPE_BOOL = 0x08,
   BSON_TYPE_DATE_TIME = 0x09,
   BSON_TYPE_NULL = 0x0A,
   BSON_TYPE_REGEX = 0x0B,
   BSON_TYPE_DBPOINTER = 0x0C,
   BSON_TYPE_CODE = 0x0D,
   BSON_TYPE_SYMBOL = 0x0E,
   BSON_TYPE_CODEWSCOPE = 0x0F,
   BSON_TYPE_INT32 = 0x10,
   BSON_TYPE_TIMESTAMP = 0x11,
   BSON_TYPE_INT64 = 0x12,
   BSON_TYPE_MAXKEY = 0x7F,
   BSON_TYPE_MINKEY = 0xFF,
} bson_type_t;


Description

The bson_type_t enumeration contains all of the types from the BSON Specification. It can be used to determine the type of a field at runtime.

Example

bson_iter_t iter;
if (bson_iter_init_find (&iter, doc, "foo") &&
    (BSON_TYPE_INT32 == bson_iter_type (&iter))) {
   printf ("'foo' is an int32.\n");
}


BSON_UINT32_TO_STRING()

Synopsis

size_t
bson_uint32_to_string (uint32_t value,
                       const char **strptr,
                       char *str,
                       size_t size);


See Array Element Key Building for example usage.

Parameters

  • value: A uint32_t.
  • strptr: A location for the resulting string pointer.
  • str: A location to buffer the string.
  • size: A size_t containing the size of str.

Description

Converts value to a string.

If value is from 0 to 999, it will use a constant string in the data section of the library.

If not, a string will be formatted using str and snprintf().

strptr will always be set. It will either point to str or a constant string. Use this as your key.

Returns

The number of bytes in the resulting string.

BSON_UNICHAR_T

Unicode Character Abstraction

Synopsis

typedef uint32_t bson_unichar_t;


Description

bson_unichar_t provides an abstraction on a single unicode character. It is the 32-bit representation of a character. As UTF-8 can contain multi-byte characters, this should be used when iterating through UTF-8 text.

Example

static void
print_each_char (const char *str)
{
   bson_unichar_t c;
   for (; *str; str = bson_utf8_next_char (str)) {
      c = bson_utf8_get_char (str);
      printf ("The numberic value is %u.\n", (unsigned) c);
   }
}


BSON_VALUE_T

BSON Boxed Container Type

Synopsis

#include <bson.h>
typedef struct _bson_value_t {
   bson_type_t value_type;
   union {
      bson_oid_t v_oid;
      int64_t v_int64;
      int32_t v_int32;
      int8_t v_int8;
      double v_double;
      bool v_bool;
      int64_t v_datetime;
      struct {
         uint32_t timestamp;
         uint32_t increment;
      } v_timestamp;
      struct {
         uint32_t len;
         char *str;
      } v_utf8;
      struct {
         uint32_t data_len;
         uint8_t *data;
      } v_doc;
      struct {
         uint32_t data_len;
         uint8_t *data;
         bson_subtype_t subtype;
      } v_binary;
      struct {
         char *regex;
         char *options;
      } v_regex;
      struct {
         char *collection;
         uint32_t collection_len;
         bson_oid_t oid;
      } v_dbpointer;
      struct {
         uint32_t code_len;
         char *code;
      } v_code;
      struct {
         uint32_t code_len;
         char *code;
         uint32_t scope_len;
         uint8_t *scope_data;
      } v_codewscope;
      struct {
         uint32_t len;
         char *symbol;
      } v_symbol;
   } value;
} bson_value_t;


Description

The bson_value_t structure is a boxed type for encapsulating a runtime determined type.

Example

const bson_value_t *value;
value = bson_iter_value (&iter);
if (value->value_type == BSON_TYPE_INT32) {
   printf ("%d\n", value->value.v_int32);
}


BSON_VISITOR_T

Synopsis

#include <bson.h>
typedef struct {
   /* run before / after descending into a document */
   bool (*visit_before) (const bson_iter_t *iter, const char *key, void *data);
   bool (*visit_after) (const bson_iter_t *iter, const char *key, void *data);
   /* corrupt BSON, or unsupported type and visit_unsupported_type not set */
   void (*visit_corrupt) (const bson_iter_t *iter, void *data);
   /* normal bson field callbacks */
   bool (*visit_double) (const bson_iter_t *iter,
                         const char *key,
                         double v_double,
                         void *data);
   bool (*visit_utf8) (const bson_iter_t *iter,
                       const char *key,
                       size_t v_utf8_len,
                       const char *v_utf8,
                       void *data);
   bool (*visit_document) (const bson_iter_t *iter,
                           const char *key,
                           const bson_t *v_document,
                           void *data);
   bool (*visit_array) (const bson_iter_t *iter,
                        const char *key,
                        const bson_t *v_array,
                        void *data);
   bool (*visit_binary) (const bson_iter_t *iter,
                         const char *key,
                         bson_subtype_t v_subtype,
                         size_t v_binary_len,
                         const uint8_t *v_binary,
                         void *data);
   /* normal field with deprecated "Undefined" BSON type */
   bool (*visit_undefined) (const bson_iter_t *iter,
                            const char *key,
                            void *data);
   bool (*visit_oid) (const bson_iter_t *iter,
                      const char *key,
                      const bson_oid_t *v_oid,
                      void *data);
   bool (*visit_bool) (const bson_iter_t *iter,
                       const char *key,
                       bool v_bool,
                       void *data);
   bool (*visit_date_time) (const bson_iter_t *iter,
                            const char *key,
                            int64_t msec_since_epoch,
                            void *data);
   bool (*visit_null) (const bson_iter_t *iter, const char *key, void *data);
   bool (*visit_regex) (const bson_iter_t *iter,
                        const char *key,
                        const char *v_regex,
                        const char *v_options,
                        void *data);
   bool (*visit_dbpointer) (const bson_iter_t *iter,
                            const char *key,
                            size_t v_collection_len,
                            const char *v_collection,
                            const bson_oid_t *v_oid,
                            void *data);
   bool (*visit_code) (const bson_iter_t *iter,
                       const char *key,
                       size_t v_code_len,
                       const char *v_code,
                       void *data);
   bool (*visit_symbol) (const bson_iter_t *iter,
                         const char *key,
                         size_t v_symbol_len,
                         const char *v_symbol,
                         void *data);
   bool (*visit_codewscope) (const bson_iter_t *iter,
                             const char *key,
                             size_t v_code_len,
                             const char *v_code,
                             const bson_t *v_scope,
                             void *data);
   bool (*visit_int32) (const bson_iter_t *iter,
                        const char *key,
                        int32_t v_int32,
                        void *data);
   bool (*visit_timestamp) (const bson_iter_t *iter,
                            const char *key,
                            uint32_t v_timestamp,
                            uint32_t v_increment,
                            void *data);
   bool (*visit_int64) (const bson_iter_t *iter,
                        const char *key,
                        int64_t v_int64,
                        void *data);
   bool (*visit_maxkey) (const bson_iter_t *iter, const char *key, void *data);
   bool (*visit_minkey) (const bson_iter_t *iter, const char *key, void *data);
   /* if set, called instead of visit_corrupt when an apparently valid BSON
    * includes an unrecognized field type (reading future version of BSON) */
   void (*visit_unsupported_type) (const bson_iter_t *iter,
                                   const char *key,
                                   uint32_t type_code,
                                   void *data);
   bool (*visit_decimal128) (const bson_iter_t *iter,
                             const char *key,
                             const bson_decimal128_t *v_decimal128,
                             void *data);
   void *padding[7];
} bson_visitor_t bson_visitor_t;


Description

The bson_visitor_t structure provides a series of callbacks that can be called while iterating a BSON document. This may simplify the conversion of a bson_t to a higher level language structure.

If the optional callback visit_unsupported_type is set, it is called instead of visit_corrupt in the specific case of an unrecognized field type. (Parsing is aborted in either case.) Use this callback to report an error like "unrecognized type" instead of simply "corrupt BSON". This future-proofs code that may use an older version of libbson to parse future BSON formats.

Example

#include <bson.h>
#include <stdio.h>
static bool
my_visit_before (const bson_iter_t *iter, const char *key, void *data)
{
   int *count = (int *) data;
   (*count)++;
   /* returning true stops further iteration of the document */
   return false;
}
static void
count_fields (bson_t *doc)
{
   bson_visitor_t visitor = {0};
   bson_iter_t iter;
   int count = 0;
   visitor.visit_before = my_visit_before;
   if (bson_iter_init (&iter, doc)) {
      bson_iter_visit_all (&iter, &visitor, &count);
   }
   printf ("Found %d fields.\n", count);
}


BSON_WRITER_T

Bulk BSON serialization Abstraction

Synopsis

#include <bson.h>
typedef struct _bson_writer_t bson_writer_t;
bson_writer_t *
bson_writer_new (uint8_t **buf,
                 size_t *buflen,
                 size_t offset,
                 bson_realloc_func realloc_func,
                 void *realloc_func_ctx);
void
bson_writer_destroy (bson_writer_t *writer);


Description

The bson_writer_t API provides an abstraction for serializing many BSON documents to a single memory region. The memory region may be dynamically allocated and re-allocated as more memory is demanded. This can be useful when building network packets from a high-level language. For example, you can serialize a Python Dictionary directly to a single buffer destined for a TCP packet.

Example

#include <bson.h>
int
main (int argc, char *argv[])
{
   bson_writer_t *writer;
   uint8_t *buf = NULL;
   size_t buflen = 0;
   bson_t *doc;
   writer = bson_writer_new (&buf, &buflen, 0, bson_realloc_ctx, NULL);
   for (i = 0; i < 1000; i++) {
      bson_writer_begin (writer, &doc);
      BSON_APPEND_INT32 (&doc, "i", i);
      bson_writer_end (writer);
   }
   bson_writer_destroy (writer);
   bson_free (buf);
   return 0;
}


SYSTEM CLOCK

BSON Clock Abstraction

Synopsis

int64_t
bson_get_monotonic_time (void);
int
bson_gettimeofday (struct timeval *tv,
                   struct timezone *tz);


Description

The clock abstraction in Libbson provides a cross-platform way to handle timeouts within the BSON library. It abstracts the differences in implementations of gettimeofday() as well as providing a monotonic (incrementing only) clock in microseconds.

MEMORY MANAGEMENT

BSON Memory Abstraction.

Description

Libbson contains a lightweight memory abstraction to make portability to new platforms easier. Additionally, it helps us integrate with interesting higher-level languages. One caveat, however, is that Libbson is not designed to deal with Out of Memory (OOM) situations. Doing so requires extreme dilligence throughout the application stack that has rarely been implemented correctly. This may change in the future. As it stands now, Libbson will abort() under OOM situations.

To aid in language binding integration, Libbson allows for setting a custom memory allocator via bson_mem_set_vtable(). This allocation may be reversed via bson_mem_restore_vtable().

LIBBSON VERSIONING

Versioning Macros and Functions

Macros

The following preprocessor macros can be used to perform various checks based on the version of the library you are compiling against. This may be useful if you only want to enable a feature on a certain version of the library.

Synopsis

#define BSON_CHECK_VERSION(major, minor, micro)
#define BSON_MAJOR_VERSION (1)
#define BSON_MINOR_VERSION (4)
#define BSON_MICRO_VERSION (1)
#define BSON_VERSION_S "1.4.1"
#define BSON_VERSION_HEX                                  \
   (BSON_MAJOR_VERSION << 24 | BSON_MINOR_VERSION << 16 | \
    BSON_MICRO_VERSION << 8)


Only compile a block on Libbson 1.1.0 and newer.

#if BSON_CHECK_VERSION(1, 1, 0)
static void
do_something (void)
{
}
#endif


AUTHOR

MongoDB, Inc

COPYRIGHT

2017, MongoDB, Inc
May 23, 2017 1.6.3