bson_t

BSON Document Abstraction

Synopsis

#include <bson/bson.h>

/**
 * bson_empty:
 * @b: a bson_t.
 *
 * Checks to see if @b is an empty BSON document. An empty BSON document is
 * a 5 byte document which contains the length (4 bytes) and a single NUL
 * byte indicating end of fields.
 */
#define bson_empty(b) /* ... */

/**
 * bson_empty0:
 *
 * Like bson_empty() but treats NULL the same as an empty bson_t document.
 */
#define bson_empty0(b) /* ... */

/**
 * bson_clear:
 *
 * Easily free a bson document and set it to NULL. Use like:
 *
 * bson_t *doc = bson_new();
 * bson_clear (&doc);
 * BSON_ASSERT (doc == NULL);
 */
#define bson_clear(bptr) /* ... */

/**
 * BSON_MAX_SIZE:
 *
 * The maximum size in bytes of a BSON document.
 */
#define BSON_MAX_SIZE /* ... */

#define BSON_APPEND_ARRAY(b, key, val) \
   bson_append_array (b, key, (int) strlen (key), val)

#define BSON_APPEND_ARRAY_BEGIN(b, key, child) \
   bson_append_array_begin (b, key, (int) strlen (key), child)

#define BSON_APPEND_BINARY(b, key, subtype, val, len) \
   bson_append_binary (b, key, (int) strlen (key), subtype, val, len)

#define BSON_APPEND_BOOL(b, key, val) \
   bson_append_bool (b, key, (int) strlen (key), val)

#define BSON_APPEND_CODE(b, key, val) \
   bson_append_code (b, key, (int) strlen (key), val)

#define BSON_APPEND_CODE_WITH_SCOPE(b, key, val, scope) \
   bson_append_code_with_scope (b, key, (int) strlen (key), val, scope)

#define BSON_APPEND_DBPOINTER(b, key, coll, oid) \
   bson_append_dbpointer (b, key, (int) strlen (key), coll, oid)

#define BSON_APPEND_DOCUMENT_BEGIN(b, key, child) \
   bson_append_document_begin (b, key, (int) strlen (key), child)

#define BSON_APPEND_DOUBLE(b, key, val) \
   bson_append_double (b, key, (int) strlen (key), val)

#define BSON_APPEND_DOCUMENT(b, key, val) \
   bson_append_document (b, key, (int) strlen (key), val)

#define BSON_APPEND_INT32(b, key, val) \
   bson_append_int32 (b, key, (int) strlen (key), val)

#define BSON_APPEND_INT64(b, key, val) \
   bson_append_int64 (b, key, (int) strlen (key), val)

#define BSON_APPEND_MINKEY(b, key) \
   bson_append_minkey (b, key, (int) strlen (key))

#define BSON_APPEND_DECIMAL128(b, key, val) \
   bson_append_decimal128 (b, key, (int) strlen (key), val)

#define BSON_APPEND_MAXKEY(b, key) \
   bson_append_maxkey (b, key, (int) strlen (key))

#define BSON_APPEND_NULL(b, key) bson_append_null (b, key, (int) strlen (key))

#define BSON_APPEND_OID(b, key, val) \
   bson_append_oid (b, key, (int) strlen (key), val)

#define BSON_APPEND_REGEX(b, key, val, opt) \
   bson_append_regex (b, key, (int) strlen (key), val, opt)

#define BSON_APPEND_UTF8(b, key, val) \
   bson_append_utf8 (b, key, (int) strlen (key), val, (int) strlen (val))

#define BSON_APPEND_SYMBOL(b, key, val) \
   bson_append_symbol (b, key, (int) strlen (key), val, (int) strlen (val))

#define BSON_APPEND_TIME_T(b, key, val) \
   bson_append_time_t (b, key, (int) strlen (key), val)

#define BSON_APPEND_TIMEVAL(b, key, val) \
   bson_append_timeval (b, key, (int) strlen (key), val)

#define BSON_APPEND_DATE_TIME(b, key, val) \
   bson_append_date_time (b, key, (int) strlen (key), val)

#define BSON_APPEND_TIMESTAMP(b, key, val, inc) \
   bson_append_timestamp (b, key, (int) strlen (key), val, inc)

#define BSON_APPEND_UNDEFINED(b, key) \
   bson_append_undefined (b, key, (int) strlen (key))

#define BSON_APPEND_VALUE(b, key, val) \
   bson_append_value (b, key, (int) strlen (key), (val))

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.

Duplicate Keys

The BSON specification allows BSON documents to have duplicate keys. Documents are stored as an ordered list of key-value pairs. A bson_t may contain duplicate keys. Applications should refrain from generating such documents, because MongoDB server behavior is undefined when a BSON document contains duplicate keys.

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);
}