.TH inviso_lfm_tpfreader 3erl "inviso 0.6.3" "Ericsson AB" "Erlang Module Definition"
.SH NAME
inviso_lfm_tpfreader \- Inviso Standard Reader Process to Standard Logfile Merger
.SH DESCRIPTION
.LP
Implements the standard reader process to the standard logfile merger \fIinviso_lfm\fR\&\&.
.LP
The reader process reads logfiles belonging to the same set (normally one node) in chronological order and delivers logged trace messages one by one to the output process\&. Before any trace messages are delivered, the \fIinviso_lfm_tpreader\fR\& implementation reads the entire trace information file (if in use) and builds a database over pid-to-alias associations\&.
.LP
The \fIinviso_lfm_tpreader\fR\& implementation is capable of considering that an alias may have been used for several processes during different times\&. An alias may also be in use for several pids at the same time, on purpose\&. If a process has generated a trace message, all associations between that pid and aliases will be presented as the list \fIPidMappings\fR\& in the message sent to the output process\&.
.SH EXPORTS
.LP
.B
handle_logfile_sort_wrapset(LogFiles) -> FileList2
.br
.RS
.LP
Types:

.RS 3
LogFiles = [{trace_log, FileList}]
.br
FileList = FileList2 = [FileName]
.br
 FileName = string()
.br
.RE
.RE
.RS
.LP
Only one \fI{trace_log, FileList}\fR\& tuple is expected in \fILogFiles\fR\&, all other tuples are ignored\&. \fIFileList\fR\& must:
.RS 2
.TP 2
*
contain one single file name, or
.LP
.TP 2
*
a list of wraplog files, following the naming convention \fI<Prefix><Nr><Suffix>\fR\&\&.
.LP
.RE

.LP
Sorts the files in \fIFileList\fR\& in chronological order beginning with the oldest\&. Sorting is only relevant if \fIFileList\fR\& is a list of wraplogs\&. The sorting is done on finding the modulo-counter in the filename and not on filesystem timestamps\&.
.LP
This function is exported for convenience should an own reader process be implemented\&.
.RE

.SH "THE TRACE INFORMATION FILE PROTOCOL"

.LP
The format of a trace information file is dictated by the meta tracer process\&. The \fIinviso_lfm_tpfreader\fR\& implementation of a reader process understands the following trace information entries\&. Note that the \fIinviso_rt_meta\fR\& trace information file is on binary format prefixing every entry with a 4 byte length indicator\&.
.RS 2
.TP 2
.B
\fI{Pid, Alias, alias, NowStamp}\fR\&:
\fIPid = pid()\fR\& 
.br
\fIAlias = term()\fR\& 
.br
\fINowStamp = term()\fR\&, but in current implementation as returned from \fIerlang:now/0\fR\&
.RS 2
.LP
This message indicates that from now on shall \fIPid\fR\& be associated with \fIAlias\fR\&\&.
.RE

.TP 2
.B
\fI{MaybePid, Alias, unalias, NowStamp}\fR\&:
\fIMaybePid = pid() | undefined\fR\& 
.br
\fIAlias = term()\fR\& 
.br
\fINowStamp = term()\fR\&, see above
.RS 2
.LP
This message indicates that, if \fIMaybePid\fR\& is a pid, this pid shall no longer be associated with \fIAlias\fR\&\&. If it is \fIundefined\fR\&, all associations with \fIAlias\fR\& from now shall be considered invalid\&.
.RE

.RS 2
.LP
Also note that there are many situations where \fIunalias\fR\& entries will be missing\&. For instance if a process terminates without making explicit function calls removing its associations first\&. This is seldom a problem unless the pid is reused\&.
.RE

.RE