Lines Matching refs:a
15 with a very large number (many hundreds, more than a thousand if
17 overhead associated with establishing a TCP connection (the overhead
18 of preparing for a new connection on the server side is insignificant
23 and responses from servers. Unstructured data is sent when a client
25 unstructured data in exactly the same way it received it, as a byte
29 of such data (either a client or a server) will always know, from a
35 may also appear inside the data. Therefore, when a client retrieves
36 data from a server, it must use the length of the data block (which it
44 Data stored by memcached is identified with the help of a key. A key
45 is a text string which should uniquely identify the data for clients
47 length limit of a key is set at 250 characters (of course, normally
57 "prepend" and "cas") ask the server to store some data identified by a
58 key. The client sends a command line, and then a data block; after
63 retrieve data corresponding to a set of keys (one or more keys in one
64 request). The client sends a command line, which includes all the
82 Meta commands are a set of new ASCII-based commands. They follow the same
83 structure of the original commands but have a new flexible feature set.
85 well as a flag system to make the commands flexible rather than having a
98 All meta commands follow a basic syntax:
102 Where <cm> is a 2 character command code.
109 Where <RC> is a 2 character return code. The number of flags returned are
115 behavior of the command. If a flag requests a response flag (ie 't' for TTL
120 behavior of a command. Flags may contain token arguments, which come after the
123 supplied in the request. Sending an 't' flag with a get for an item with 20
126 All commands accept a tokens 'P' and 'L' which are completely ignored. The
127 arguments to 'P' and 'L' can be used as hints or path specifications to a
128 proxy or router inbetween a client and a memcached daemon. For example, a
129 client may prepend a "path" in the key itself: "mg /path/foo v" or in a proxy
131 token to a memcached daemon, which will ignore them.
142 Some commands involve a client sending some kind of expiration time
145 Unix time (number of seconds since January 1, 1970, as a 32-bit
146 value), or a number of seconds starting from current time. In the
148 of seconds in 30 days); if the number sent by a client is larger than
152 Note that a TTL of 1 will sometimes immediately expire. Time is internally
159 Each command sent by a client may be answered with an error string
164 means the client sent a nonexistent command name.
169 doesn't conform to the protocol in some way. <error> is a
175 out the command. <error> is a human-readable error string. In cases
179 case in which the server closes a connection to a client.
190 sending a fake "set" command with any key:
207 First, the client sends a command line which looks like this:
230 "cas" is a check and set operation which means "store this data but
237 when the item is retrieved. Clients may use this as a bit field to
248 server time). If a negative value is given the item is immediately
255 - <cas unique> is a unique 64-bit value of an existing entry.
269 - <data block> is a chunk of arbitrary 8-bit data of length <bytes>
279 condition for an "add" or a "replace" command wasn't met.
282 a "cas" command has been modified since you last fetched it.
285 with a "cas" command did not exist.
299 which is received as a text line followed by a data block. After all
318 - <cas unique> is a unique 64-bit integer that uniquely identifies
323 If some of the keys appearing in a retrieval request are not sent back
327 deleted by a client).
359 treated as decimal representation of a 64-bit unsigned integer. If
360 the current data value does not conform to such a representation, the
364 that a non-existent key exists with value 0; instead, they will fail.
377 the item. It is a decimal representation of a 64-bit unsigned integer.
390 Note that underflow in the "decr" command is caught: if a client tries
394 Note also that decrementing a number such that it loses length isn't
439 which is received as a text line followed by a data block. After all
458 - <cas unique> is a unique 64-bit integer that uniquely identifies
466 The meta debug command is a human readable dump of all available internal
472 - if <flag> is 'b', then <key> is a base64 encoded binary value. the response
503 - <key> means one key string. Unlike "get" metaget can only take a single key.
505 - <flags> are a set of single character codes ended with a space or newline.
508 After this command, the client expects an item to be returned, received as a
511 If a response line appearing in a retrieval request is not sent back
515 deleted by a client).
530 If the request did not ask for a value in the response (v) flag, the server
535 If the request resulted in a miss, the response looks like:
539 Unless the (q) flag was supplied, which suppresses the status code for a miss.
546 - h: return whether item has been hit before as a 0 or 1
547 - k: return key as a token
549 - O(token): opaque value, consumes a token and copies back with response
558 - N(token): vivify on miss, takes TTL as a argument
565 - Z: item has already sent a winning flag
571 This flag instructs memcached to run a base64 decoder on <key> before looking
575 If 'b' flag is sent in the response, and a key is returned via 'k', this
578 - h: return whether item has been hit before as a 0 or 1
582 before the command was processed. Otherwise this would always show a 1 for
585 - O(token): opaque value, consumes a token and copies back with response
591 long this can generate a lot of traffic, especially if the data block is very
595 Opaque tokens may be up to 32 bytes in length, and are a string similar to
600 Noreply is a method of reducing the amount of data sent back by memcached to
619 The data block for a metaget response is optional, requiring this flag to be
625 Normally when an item is created it is given a CAS value from an internal
630 - N(token): vivify on miss, takes TTL as a argument
634 create a stub item with the key and TTL as supplied. If such an item is
635 created a 'W' flag is added to the response to indicate to a client that they
640 Further requests will see a 'Z' flag to indicate that another client has
648 below the supplied token, return a 'W' flag to indicate the client has "won"
650 a miss.
660 When combined with N or R flags, a client may be informed they have "won"
661 ownership of a cache item. This allows a single client to be atomically
672 client that an object needs to be updated, and that it should make a decision
678 - Z: item has already sent a winning flag
681 flag indicates to a client that a different client is responsible for
688 The meta set command a generic command for storing data to memcached. Based
698 - <flags> are a set of single character codes ended with a space or newline.
705 - <data block> is a chunk of arbitrary 8-bit data of length supplied by an 'S'
735 - k: return key as a token
736 - O(token): opaque value, consumes a token and copies back with response
752 matches the current CAS value of the item. When combined with the 'I' flag, a
764 - O(token): opaque value, consumes a token and copies back with response
770 Noreply is a method of reducing the amount of data sent back by memcached to
771 the client for normal responses. In the case of metaset, a response that
777 - M(token): mode switch. Takes a single character for the mode.
787 Append and Prepend modes will also respect a supplied cas value.
792 a new item on a miss. If N is supplied, and append reaches a miss, it will
793 create a new item seeded with the data from the append command. It uses the
807 - <flags> are a set of single character codes ended with a space or newline.
839 Can be used to only delete or mark-stale if a supplied CAS value matches.
843 Instead of removing an item, this will give the item a new CAS value and mark
865 item atomically). Combined with I this can leave what is effectively a
866 tombstone of a previous value.
880 - <flags> are a set of single character codes ended with a space or newline.
894 after a miss.
914 - O(token): opaque value, consumes a token and copies back with response
919 - k: return key as a token
925 Can be used to only incr/decr if a supplied CAS value matches. A new CAS value
926 is generated after a delta is applied. Add the 'c' flag to get the new CAS
931 Similar to mget, on a miss automatically create the item. A value can be
936 An unsigned 64-bit integer which will be seeded as the value on a miss. Must be
948 -M(token): mode switch. Takes a single character for the mode.
958 The meta no-op command exists solely to return a static response code. It
971 "MN\r\n", signalling to a client that all previous commands have been
979 The slabs reassign command is used to redistribute memory once a running
985 - <source class> is an id number for the slab class to steal a page from
989 - <dest class> is an id number for the slab class to move a page to
995 - "BUSY [message]" to indicate a page is already being processed, try again
998 - "BADCLASS [message]" a bad class id was specified
1004 - "UNSAFE [message]" source class cannot move a page right now
1013 The slabs automove command enables a background thread which decides on its
1028 - <1> means to return pages to a global pool when there are more than 2 pages
1029 worth of free chunks in a slab class. Pages are then re-assigned back into
1032 - <2> is a highly aggressive mode which causes pages to be moved every time
1039 Memcached supports multiple LRU algorithms, with a few tunables. Effort is
1043 The traditional model is "flat" mode, which is a single LRU chain per slab
1045 HOT, WARM, COLD. There is also a TEMP LRU. See doc/new_lru.txt for details.
1061 zero or above, items set with a TTL lower than this will go into TEMP_LRU
1067 - "OK" to indicate a successful update of the settings.
1069 - "ERROR [message]" to indicate a failure or improper arguments.
1079 items. This is useful if you have a mix of items with both long and short
1103 - "CLIENT_ERROR [message]" indicating a format or bounds issue.
1107 - The maximum number of items to inspect in a slab class per run request. This
1115 - "CLIENT_ERROR [message]" indicating a format or bound issue.
1119 - Takes a single, or a list of, numeric classids (ie: 1,3,10). This instructs
1131 - "BUSY [message]" to indicate the crawler is already processing a request.
1142 if "hash" is specified instead of a classid or "all", the crawler will dump
1148 (ie: %20 for a space).
1159 - "BUSY [message]" to indicate the crawler is already processing a request.
1168 If "hash" is specified instead of a classid or "all", the crawler will dump
1173 Lines are in a basic metaget format, like: "mg key\r\n". If a key is in
1182 - "BUSY [message]" to indicate the crawler is already processing a request.
1191 Watchers are a way to connect to memcached and inspect what's going on
1207 - Turn connection into a watcher. Options can be stacked and are
1217 Lines are prepending with "ts=" for a timestamp and "gid=" for a global ID
1230 This means a "set" command would also emit an item_get log, as it checks for
1242 address IP and port. Connection close events additionally supply a reason for
1247 returned to a client while in proxy mode. The conditions which logs are
1282 a number of lines which look like this:
1295 In the type column below, "32u" means a 32-bit unsigned integer, "64u"
1296 means a 64-bit unsigned integer. '32u.32u' means two 32-bit unsigned
1297 integers separated by a colon (treat this as a floating point number).
1326 | response_obj_bytes | 64u | Total bytes used for resp. objects. is a |
1360 | cas_badval | 64u | Number of CAS reqs for which a key was |
1363 | | | with a new expiration time |
1367 | | | caused by attempting to write a value |
1399 | | | grown to a new size |
1407 | slab_reassign_running | bool | If a slab page is being moved |
1425 | | 64u | Valid items evicted during a page move |
1429 | | | during a page move. |
1435 | | 64u | Items busy during page move, requiring a |
1440 | log_worker_dropped | 64u | Logs a worker never wrote due to full buf |
1441 | log_worker_written | 64u | Logs written by a worker, to be picked up |
1519 | track_sizes | bool | If yes, a "stats sizes" histogram is being |
1575 store a new item. This means you are running with -M or
1577 tailrepairs Number of times we self-healed a slab with a refcount
1578 leak. If this counter is increasing a lot, please
1597 tails to find memory for a new item.
1606 * Items are stored in a slab that is the same size or larger than the
1607 item. mem_requested shows the size of all items within a
1609 wasted in a slab class. If you see a lot of waste, consider tuning
1635 This is essentially a display of all of your items if there was a slab class
1659 The feature can still be enabled at start time via `-o track_sizes` and has a
1662 If you want to make a histogram of item sizes for a memcached instance that is
1698 | cas_badval | Total number of CAS commands that failed to modify a |
1699 | | value due to a bad CAS id. |
1737 | | "state" indicates a command is currently executing, |
1748 | conn_listening | Listening for new connections or a new UDP request. |
1749 | conn_mwrite | Writing a complex response, e.g., to a "get" command. |
1750 | conn_new_cmd | Connection is being prepared to accept a new command. |
1751 | conn_nread | Reading extended data, typically for a command such as |
1753 | conn_parse_cmd | The server has received a command and is in the middle |
1761 | conn_write | Writing a simple response (anything that doesn't involve |
1768 TLS is a compile-time opt-in feature available in versions 1.5.13 and later.
1778 | ssl_proto_errors | 64u | Number of times a client has |
1779 | | | seen a fatal TLS protocol error|
1796 "flush_all" is a command with an optional numeric argument. It always
1801 response to a retrieval command (unless it's stored again under the
1809 The intent of flush_all with a delay, was that in a setting where you
1810 have a pool of memcached servers, and you need to flush all content,
1812 same time (which could e.g. cause a spike in database load with all
1820 "cache_memlimit" is a command with a numeric argument. This allows runtime
1830 "shutdown" is a command with an optional argument used to stop memcached with
1831 a kill signal. By default, "shutdown" alone raises SIGINT, though "graceful"
1832 may be specified as the single argument to instead trigger a graceful shutdown
1836 "version" is a command with no arguments:
1845 "verbosity" is a command with a numeric argument. It always succeeds,
1850 "quit" is a command with no arguments:
1864 "misbehave" is a command with no arguments:
1868 This command causes the worker thread to attempt a) opening a new socket, and
1869 b) executing a shell command. If either one is successful, an error is
1879 also a UDP-based interface. The UDP interface does not provide guaranteed
1881 succeed; typically it is used for "get" requests where a missing or
1882 incomplete response can simply be treated as a cache miss.
1884 Each UDP datagram contains a simple frame header, followed by data in the
1886 implementation, requests must be contained in a single UDP datagram, but
1900 The request ID is supplied by the client. Typically it will be a
1901 monotonically increasing value starting from a random seed, but the client
1911 datagrams for a given response in sequence number order; the resulting byte
1912 stream will contain a complete response in the same format as the TCP