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diff --git a/doc/rainerscript.html b/doc/rainerscript.html index aaaced40..0a780ac4 100644 --- a/doc/rainerscript.html +++ b/doc/rainerscript.html @@ -37,44 +37,22 @@ script interpreter when there is need to do so.<br> <h2>Variable (Property) types</h2> <p>All rsyslog properties (see the <a href="property_replacer.html">property replacer</a> page for a list) can be used in RainerScript. In addition, it also -supports local and global variables. Local variables are local to the current message, but are +supports local variables. Local variables are local to the current message, but are NOT message properties (e.g. the "$!" all JSON property does not contain -them). Global variables have a truely global scope and are NOT bound to -a specifc message. Thus they can be used to persist values across -multiple messages (for things like counters). Please note that rsyslog -ensures proper synchronization for global variables (which also means -they are slower than the others). HOWEVER, in a highly multithreaded -configuration operations like<br> -set $/var = $/var + 1;</br> -are <b>not</b> atomic, so some updates to the counter variable may be missing. The -classical sample for this is in a two-thread environment: Variable $/var is set -to 1 at the start. Now the following happens in the following order: -<ol> -<li>Thread A reads 1 from $/var and adds 1, result is 2, but not yet stored -<li>Thread B reads 1 from $/var and adds 1, result is 2, but not yet stored -<li>Thread A stores its result of 2 -<li>Thread B stores its result of 2 -</ol> -After this sequence, $/var contains the value two, which is probably not what was -expected. Rsyslog does <b>not</b> provide looking primitives for individual variables, -as this can lead to serious configuration problems if not used 100% correctly. -However, rsyslog provides (or will in the future provide) special function which -provide guaranteed atomic updates (in the sample, the end result would be three -no matter what the scheduling order is). +them). <p>Only message json (CEE/Lumberjack) properties can be modified by the "set" and "unset" statements, not any other message property. Obviously, -local and global variables are also modifieable. +local variables are also modifieable. <p>Message JSON property names start with "$!" where the bang character represents the root. -<p>Local variables names start with "$.", where the dot denotes the root. Similarly, -global variables start with "$/". -<p>Both JSON properties as well as global/local variables may contain an arbitrary +<p>Local variables names start with "$.", where the dot denotes the root. +<p>Both JSON properties as well as local variables may contain an arbitrary deep path before the final element. The bang character is always used as path -separator, no matter if it is a message property or a global/local variable. For example +separator, no matter if it is a message property or a local variable. For example "$!path1!path2!varname" is a three-level deep message property where as the very similar looking "$.path1!path2!varname" specifies a three-level -deep local variable. The similar global variables is named "$/path1!path2!varname". -The bang, slash, or dot character immediately following the +deep local variable. +The bang or dot character immediately following the dollar sign is used by rsyslog to separate the different types. <h2>configuration objects</h2> <h3>main_queue()</h3> |