mcl.c. Because of the nature of the fanout function, which blocks waiting
on RMR messages, it is not possible to unit test that bit of code.
+
+Data Capture
+In addition to writing received messages to a FIFO, each message is
+captured in a raw data file. These files are created in a staging
+directory (/tmp/rdc/stage by default) and moved to a final directory
+(/tmp/rdc/final by default) every 5 minutes (300 seconds). The files
+are named MCLT[src]_<timestamp><.suffix>; the default suffix is ".rdc".
+The "src" string is optional and can be used to disabmiguate files
+if merged with capture files from different environments.
+
+The data capture is controlled by setting environment variables:
+
+ MCL_RDC_ENABLE: If set to 0 the raw data capture will be disabled.
+ (It is on by default if this variable is not defined.)
+
+ MCL_RDC_STAGE: overrides the directory where raw data capture
+ files are staged.
+
+ MCL_RDC_FINAL: overrides the directory where raw data capture files
+ are placed for export.
+
+ MCL_RDC_SUFFIX: the suffix written on each raw data capture file;
+ must include '.' if a dot is desired and is written only on
+ the final file (not the staged file).
+
+ MCL_RDC_SOURCE: a short string used as source identification in rdc file names.
+ This defaults to nothing and should begin, but not end,
+ with an underbar (e.g. _host1).
+
+ MCL_RDC_FREQ: The frequency with which files are closed and moved from the
+ staging to final directory. The default if 300 sec.
+
+The captured data is saved in the following format:
+ <delim><mtype><len><fifo-buffer>
+
+Where
+ <delim> is a 4 character delimiter for synchronisation (@RDC)
+
+ <mtype> is an 8 character field containing a nil terminated ACII
+ value that is the message type of the received message.
+
+ <len> is an 8 character field containing a nil terminated ASCII
+ value that is the length of the <fifo-buffer>
+
+ <fifo-buffer> is the exact contents that were written to the FIFO.
+
+Thus to "replay" the captured data, a decoder need read just the first
+20 bytes, convert the message type and length, read the payload, and
+then write the payload to a FIFO
+
+Staging and Final Directories
+If the staging and final directories (/tmp/rdc/stage and /tmp/rdc/final
+by default) are on the same filsystem, then the rename() system call is
+used to switch the inode reference to the file from one directory to the
+other. This is the preferred setup. However, if it is not possible for
+these directories to exist on the same filesystem, then the listener will
+copy the file "manually." During the copy, the filename in the final
+directory will have a leading dot (.) charcter, and the file will be
+created with a write only by owner mode (0200) and not switched to readable
+until after it is closed; just before renaming it to remove the leading
+dot.
+
+Any file capture utillity should either ignore files with leading dot
+characters, or files which do not have a read bit set in their mode.
+
+
+
FIFO Reader
The pipe_reader programme is a simple application which uses the mcl.c
library functions to open and read from a single pipe. If the -e option
is given it will expect that data in the FIFO has extended headers. Use
the -? option (or -h) to generate a full usage statement.
+
+
Code Review / ric-app / mc.git / blobdiff