diff options
Diffstat (limited to 'src/rabbit_guid.erl')
| -rw-r--r-- | src/rabbit_guid.erl | 26 |
1 files changed, 19 insertions, 7 deletions
diff --git a/src/rabbit_guid.erl b/src/rabbit_guid.erl index 2be00503..b789fbd1 100644 --- a/src/rabbit_guid.erl +++ b/src/rabbit_guid.erl @@ -42,6 +42,7 @@ terminate/2, code_change/3]). -define(SERVER, ?MODULE). +-define(SERIAL_FILENAME, "rabbit_serial"). -record(state, {serial}). @@ -59,17 +60,28 @@ %%---------------------------------------------------------------------------- start_link() -> - %% The persister can get heavily loaded, and we don't want that to - %% impact guid generation. We therefore keep the serial in a - %% separate process rather than calling rabbit_persister:serial/0 - %% directly in the functions below. gen_server:start_link({local, ?SERVER}, ?MODULE, - [rabbit_persister:serial()], []). + [update_disk_serial()], []). + +update_disk_serial() -> + Filename = filename:join(rabbit_mnesia:dir(), ?SERIAL_FILENAME), + Serial = case rabbit_misc:read_term_file(Filename) of + {ok, [Num]} -> Num; + {error, enoent} -> rabbit_persister:serial(); + {error, Reason} -> + throw({error, {cannot_read_serial_file, Filename, Reason}}) + end, + case rabbit_misc:write_term_file(Filename, [Serial + 1]) of + ok -> ok; + {error, Reason1} -> + throw({error, {cannot_write_serial_file, Filename, Reason1}}) + end, + Serial. %% generate a guid that is monotonically increasing per process. %% %% The id is only unique within a single cluster and as long as the -%% persistent message store hasn't been deleted. +%% serial store hasn't been deleted. guid() -> %% We don't use erlang:now() here because a) it may return %% duplicates when the system clock has been rewound prior to a @@ -77,7 +89,7 @@ guid() -> %% now() to move ahead of the system time), and b) it is really %% slow since it takes a global lock and makes a system call. %% - %% rabbit_persister:serial/0, in combination with self/0 (which + %% A persisted serial number, in combination with self/0 (which %% includes the node name) uniquely identifies a process in space %% and time. We combine that with a process-local counter to give %% us a GUID that is monotonically increasing per process. |