Support human-friendly Thread ID in logging messages (DM-4756) #9
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| namespace log { | ||
| namespace detail { | ||
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| int lwpID() { |
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I'm not too fond of having his return an int. The lwp ID should be unsigned.
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Well, it's a bit more complicated. LWP ID is actually a process ID which is of pid_t type, and on Linux that type is int. The only possible issue here is that on systems without LWP support we use incremental counter which could overflow and become negative. I'll think about adding protection against negative values. I could change int here to pid_t too if we don't care about systems that don't define that type.
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Thinking again, I do not want to care about overflow, no reasonable application should create more than 2 billion threads during its lifetime.
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So, don't think, and use unsigned :-)
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OK, switched to unsigned for lwpID()
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| @@ -404,6 +407,66 @@ This has to be done after fork() and corresponding formatting code needs to be a | |||
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| log4j.appender.FILE.layout.conversionPattern=%X{PID} - %m%n | |||
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| \subsection TID Display thread ID | |||
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| The conversion pattern in log4cxx has special conversion code (`%t`) to render "thread ID", the rendered value is a pointer to `thread_t` object (on POSIX systems) and is rendered as a long string of hexadecimal digits which makes it difficult to read for non-hardcore programmers. `lsst.log` provides more himan-friendly way to print thread-identifying information. Special function `lsst::log::lwpID()` returns light-weight process ID (LWP) on the plaftorms that support this feature and small incremental integer number on other platforms. Using this function one can add LWP to MDC and configure output format to include this special MDC key: | |||
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To err is himan 👽
Also added lsst::log::lwpID() method which returns LWP ID or a simulated integer value (this is just a wrapper for detail::lwpID() added earlier).
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Adding new macro LOG_MDC_INIT to support dynamic MDC initialization.
LOG_MDC_INIT macro takes a function which will be executed in every new thread to update MDC. Documentation updated to describe details.