log_mf_h (stdlib v7.0)

View Source

An event handler that logs events to disk.

This module is a gen_event handler module that can be installed in any gen_event process. It logs onto disk all events that are sent to an event manager. Each event is written as a binary, which makes the logging very fast. However, a tool such as the Report Browser (rb) must be used to read the files. The events are written to multiple files. When all files have been used, the first one is reused and overwritten. The directory location, the number of files, and the size of each file are configurable. The directory will include one file called index, and report files 1, 2, ....

See Also

gen_event, rb

Summary

Types

args()

Term to be sent to gen_event:add_handler/3.

b()
f()
pred()

Functions

init(Dir, MaxBytes, MaxFiles)

Equivalent to init(Dir, MaxBytes, MaxFiles, fun(_) -> true end).

init(Dir, MaxBytes, MaxFiles, Pred)

Initiates the event handler. Returns Args, which is to be used in a call to gen_event:add_handler(EventMgr, log_mf_h, Args).

Types

args()

-opaque args()

Term to be sent to gen_event:add_handler/3.

b()

(not exported) 
-type b() :: non_neg_integer().

f()

(not exported) 
-type f() :: 1..255.

pred()

(not exported) 
-type pred() :: fun((term()) -> boolean()).

Functions

init(Dir, MaxBytes, MaxFiles)

-spec init(Dir, MaxBytes, MaxFiles) -> Args
              when
                  Dir :: file:filename(),
                  MaxBytes :: non_neg_integer(),
                  MaxFiles :: 1..255,
                  Args :: args().

Equivalent to init(Dir, MaxBytes, MaxFiles, fun(_) -> true end).

init(Dir, MaxBytes, MaxFiles, Pred)

-spec init(Dir, MaxBytes, MaxFiles, Pred) -> Args
              when
                  Dir :: file:filename(),
                  MaxBytes :: non_neg_integer(),
                  MaxFiles :: 1..255,
                  Pred :: fun((Event :: term()) -> boolean()),
                  Args :: args().

Initiates the event handler. Returns Args, which is to be used in a call to gen_event:add_handler(EventMgr, log_mf_h, Args).

Dir specifies which directory to use for the log files. MaxBytes specifies the size of each individual file. MaxFiles specifies how many files are used. Pred is a predicate function used to filter the events. If no predicate function is specified, all events are logged.