X-Git-Url: https://git.m6w6.name/?a=blobdiff_plain;f=docs%2Fmemcached_get.rst;h=d3f5806ff1e6fef62889e13a98009269040f39a8;hb=a96430cd62ea426e2874c373b486fe07cce82f03;hp=dcb931c77e9a31ee7bab44d592ed7814ad6c8c12;hpb=67456d74f5bd4f354a360d70da503dc58cbe5971;p=m6w6%2Flibmemcached diff --git a/docs/memcached_get.rst b/docs/memcached_get.rst index dcb931c7..d3f5806f 100644 --- a/docs/memcached_get.rst +++ b/docs/memcached_get.rst @@ -2,6 +2,7 @@ Retrieving data from the server =============================== +.. index:: object: memcached_st -------- SYNOPSIS @@ -36,75 +37,67 @@ DESCRIPTION ----------- -memcached_get() is used to fetch an individual value from the server. You -must pass in a key and its length to fetch the object. You must supply +:c:func:`memcached_get()` is used to fetch an individual value from the server. +You must pass in a key and its length to fetch the object. You must supply three pointer variables which will give you the state of the returned -object. A uint32_t pointer to contain whatever flags you stored with the value, -a size_t pointer which will be filled with size of of the object, and a -memcached_return_t pointer to hold any error. The object will be returned -upon success and NULL will be returned on failure. Any object returned by -memcached_get() must be released by the caller application. - -memcached_mget() is used to select multiple keys at once. For multiple key -operations it is always faster to use this function. This function always -works asynchronously. memcached_fetch() is then used to retrieve any keys -found. No error is given on keys that are not found. You must call either -memcached_fetch() or memcached_fetch_result() after a successful call to -memcached_mget(). You should continue to call these functions until they -return NULL (aka no more values). If you need to quit in the middle of a -memcached_get() call, execute a memcached_quit(). After you do this, you can -issue new queries against the server. - -memcached_fetch() is used to fetch an individual value from the server. -memcached_mget() must always be called before using this method. You -must pass in a key and its length to fetch the object. You must supply +object. A :c:type:`uint32_t` pointer to contain whatever flags you stored with the value, a :c:type:`size_t` pointer which will be filled with size of of +the object, and a :c:type:`memcached_return_t` pointer to hold any error. The +object will be returned upon success and NULL will be returned on failure. Any +object returned by :c:func:`memcached_get()` must be released by the caller +application. + +:c:func:`memcached_mget()` is used to select multiple keys at once. For +multiple key operations it is always faster to use this function. This function always works asynchronously. :c:func:`memcached_fetch()` is then used to +retrieve any keys found. No error is given on keys that are not found. You +must call either :c:func:`memcached_fetch()` or +:c:func:`memcached_fetch_result()` after a successful call to +:c:func:`memcached_mget()`. You should continue to call these functions until +they return NULL (aka no more values). If you need to quit in the middle of a +:c:func:`memcached_get()` call, execute a :c:func:`memcached_quit()`. After you do this, you can issue new queries against the server. + +:c:func:`memcached_fetch()` is used to fetch an individual value from the server. :c:func:`memcached_mget()` must always be called before using this method. +You must pass in a key and its length to fetch the object. You must supply three pointer variables which will give you the state of the returned -object. A uint32_t pointer to contain whatever flags you stored with the value, -a size_t pointer which will be filled with size of of the object, and a -memcached_return_t pointer to hold any error. The object will be returned -upon success and NULL will be returned on failure. MEMCACHD_END is returned -by the \*error value when all objects that have been found are returned. -The final value upon MEMCACHED_END is null. Values returned by -memcached_fetch() must be freed by the caller. memcached_fetch() will -be DEPRECATED in the near future, memcached_fetch_result() should be used -instead. - -memcached_fetch_result() is used to return a memcached_result_st(3) structure -from a memcached server. The result object is forward compatible with changes -to the server. For more information please refer to the memcached_result_st(3) -help. This function will dynamically allocate a result structure for you -if you do not pass one to the function. - -memcached_fetch_execute() is a callback function for result sets. Instead -of returning the results to you for processing, it passes each of the +object. A :c:type:`uint32_t` pointer to contain whatever flags you stored with the value, a :c:type:`size_t` pointer which will be filled with size of of the +object, and a :c:type:`memcached_return_t` pointer to hold any error. The +object will be returned upon success and NULL will be returned on failure. :c:type:`MEMCACHD_END` is returned by the \*error value when all objects that have been found are returned. The final value upon :c:type:`MEMCACHED_END` is null. +Values returned by :c:func:`memcached_fetch()` must be freed by the caller. +:c:func:`memcached_fetch()` will be DEPRECATED in the near future, +c:func:`memcached_fetch_result()` should be used instead. + +:c:func:`memcached_fetch_result()` is used to return a :c:type:`memcached_result_st` structure from a memcached server. The result object is forward compatible +with changes to the server. For more information please refer to the +:c:type:`memcached_result_st` help. This function will dynamically allocate a +result structure for you if you do not pass one to the function. + +:c:func:`memcached_fetch_execute()` is a callback function for result sets. +Instead of returning the results to you for processing, it passes each of the result sets to the list of functions you provide. It passes to the function -a memcached_st that can be cloned for use in the called function (it can not -be used directly). It also passes a result set which does not need to be freed. -Finally it passes a "context". This is just a pointer to a memory reference -you supply the calling function. Currently only one value is being passed -to each function call. In the future there will be an option to allow this -to be an array. - -memcached_mget_execute() and memcached_mget_execute_by_key() is -similar to memcached_mget(), but it may trigger the supplied callbacks -with result sets while sending out the queries. If you try to perform -a really large multiget with memcached_mget() you may encounter a -deadlock in the OS kernel (it will fail to write data to the socket because -the input buffer is full). memcached_mget_execute() solves this -problem by processing some of the results before continuing sending -out requests. Please note that this function is only available in the -binary protocol. - -memcached_get_by_key() and memcached_mget_by_key() behave in a similar nature -as memcached_get() and memcached_mget(). The difference is that they take -a master key that is used for determining which server an object was stored -if key partitioning was used for storage. - -All of the above functions are not tested when the \ ``MEMCACHED_BEHAVIOR_USE_UDP``\ -has been set. Executing any of these functions with this behavior on will result in -\ ``MEMCACHED_NOT_SUPPORTED``\ being returned, or for those functions which do not return -a \ ``memcached_return_t``\ , the error function parameter will be set to -\ ``MEMCACHED_NOT_SUPPORTED``\ . +a :c:type:`memcached_st` that can be cloned for use in the called +function (it can not be used directly). It also passes a result set which does +not need to be freed. Finally it passes a "context". This is just a pointer to +a memory reference you supply the calling function. Currently only one value +is being passed to each function call. In the future there will be an option +to allow this to be an array. + +:c:func:`memcached_mget_execute()` and :c:func:`memcached_mget_execute_by_key()` +is similar to :c:func:`memcached_mget()`, but it may trigger the supplied +callbacks with result sets while sending out the queries. If you try to +perform a really large multiget with :c:func:`memcached_mget()` you may +encounter a deadlock in the OS kernel (it will fail to write data to the +socket because the input buffer is full). :c:func:`memcached_mget_execute()` +solves this problem by processing some of the results before continuing +sending out requests. Please note that this function is only available in +the binary protocol. + +:c:func:`memcached_get_by_key()` and :c:func:`memcached_mget_by_key()` behave +in a similar nature as :c:func:`memcached_get()` and :c:func:`memcached_mget()`. +The difference is that they take a master key that is used for determining +which server an object was stored if key partitioning was used for storage. + +All of the above functions are not tested when the +:c:type:`MEMCACHED_BEHAVIOR_USE_UDP` has been set. Executing any of these +functions with this behavior on will result in :c:type:`MEMCACHED_NOT_SUPPORTED` being returned, or for those functions which do not return a :c:type:`memcached_return_t`, the error function parameter will be set to :c:type:`MEMCACHED_NOT_SUPPORTED`. ------ @@ -113,11 +106,20 @@ RETURN All objects returned must be freed by the calling application. -memcached_get() and memcached_fetch() will return NULL on error. You must -look at the value of error to determine what the actual error was. +:c:func:`memcached_get()` and :c:func:`memcached_fetch()` will return NULL on +error. You must look at the value of error to determine what the actual error +was. -MEMCACHED_KEY_TOO_BIG is set to error whenever memcached_fetch() was used -and the key was set larger then MEMCACHED_MAX_KEY, which was the largest +:c:func:`memcached_fetch_execute()` return :c:type:`MEMCACHED_SUCCESS` if +all keys were successful. :c:type:`MEMCACHED_NOTFOUND` will be return if no +keys at all were found. + +:c:func:`memcached_fetch()` and :c:func:`memcached_fetch_result()` set error +to :c:type:`MEMCACHED_END` upon successful conclusion. +:c:type:`MEMCACHED_NOTFOUND` will be return if no keys at all were found. + +:c:type:`MEMCACHED_KEY_TOO_BIG` is set to error whenever :c::func:`memcached_fetch()` was used +and the key was set larger then :c:type:`MEMCACHED_MAX_KEY`, which was the largest key allowed for the original memcached ascii server.