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| author | Robb Matzke <matzke@llnl.gov> | 1998-08-19 22:46:31 (GMT) |
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| committer | Robb Matzke <matzke@llnl.gov> | 1998-08-19 22:46:31 (GMT) |
| commit | e455040749ca1d47fb218b9bb35d78247fb9561d (patch) | |
| tree | 2d26f2ae1fea1ff393f00eb36e3f2155dec690b6 /doc/html/tracing.html | |
| parent | 4322bfe90ab7de7245ff770155867fa5da78147c (diff) | |
| download | hdf5-e455040749ca1d47fb218b9bb35d78247fb9561d.zip hdf5-e455040749ca1d47fb218b9bb35d78247fb9561d.tar.gz hdf5-e455040749ca1d47fb218b9bb35d78247fb9561d.tar.bz2 | |
[svn-r606] Debugging can be enabled/disabled at runtime though code is still
conditionally included at compile time. Tracing and debugging share
the same environment variable. All is documented in Debugging.html.
Diffstat (limited to 'doc/html/tracing.html')
| -rw-r--r-- | doc/html/tracing.html | 193 |
1 files changed, 0 insertions, 193 deletions
diff --git a/doc/html/tracing.html b/doc/html/tracing.html deleted file mode 100644 index 8d3c677..0000000 --- a/doc/html/tracing.html +++ /dev/null @@ -1,193 +0,0 @@ -<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN"> -<html> - <head> - <title>API Tracing</title> - </head> - - <body> - <h1>API Tracing</h1> - - <h2>Introduction</h2> - - <p>The HDF5 library is now able to trace API calls by printing the - function name, the argument names and their values, and the - return value. Some people like to see lots of output during - program execution instead of using a good symbolic debugger, and - this feature is intended for their consumption. For example, - the output from <code>h5ls foo</code> after turning on tracing, - includes: - - <p> - <center> - <table border align=center width="100%"> - <caption align=top><b>Sample Output</b></caption> - <tr> - <td> - <code><pre> -H5Tcopy(type=184549388) = 184549419 (type); -H5Tcopy(type=184549392) = 184549424 (type); -H5Tlock(type=184549424) = SUCCEED; -H5Tcopy(type=184549393) = 184549425 (type); -H5Tlock(type=184549425) = SUCCEED; -H5Fopen(filename="foo", flags=0, access=H5P_DEFAULT) = FAIL; -HDF5-DIAG: Error detected in thread 0. Back trace follows. - #000: H5F.c line 1245 in H5Fopen(): unable to open file - major(04): File interface - minor(10): Unable to open file - #001: H5F.c line 846 in H5F_open(): file does not exist - major(04): File interface - minor(10): Unable to open file - </pre></code> - </td> - </tr> - </table> - </center> - - <h2>Configuation</h2> - - <p>This all happens with some magic in the configuration script, - the makefiles, and macros. First, from the end-user point of - view, the library must be configured with the - <code>--enable-trace</code> switch (the default; - `--disable-trace' is the alternative). This causes the library - to include the support necessary for API tracing. - - <p> - <center> - <table border align=center width="100%"> - <caption align=top><b>Configuration</b></caption> - <tr> - <td> - <code><pre> -$ make distclean -$ sh configure --enable-trace -$ make - </pre></code> - </td> - </tr> - </table> - </center> - - <h2>Execution</h2> - - <p>In order to actually get tracing output one must turn tracing - on and specify a file descriptor where the tracing output should - be written. This is done by assigning a file descriptor number - to the <code>HDF5_TRACE</code> environment variable. - - <p> - <center> - <table border align=center width="100%"> - <caption align=top><b>Execution Examples</b></caption> - <tr> - <td>To display the trace on the standard error stream: - <code><pre> -$ export HDF5_TRACE=2 -$ a.out - </pre></code> - </td> - </tr> - <tr> - <td>To send the trace to a file: - <code><pre> -$ export HDF5_TRACE=255 -$ a.out 255>trace-output - </pre></code> - </td> - </tr> - </table> - </center> - - <h2>Performance</h2> - - <p>If the library was not configured for tracing then there is no - unnecessary overhead since all tracing code is - excluded. - - <p>However, if tracing is enabled but not used there is a - small penalty. First, code size is larger because of extra - statically-declared character strings used to store argument - types and names and extra auto variable pointer in each - function. Also, execution is slower because each function sets - and tests a local variable and each API function calls the - <code>H5_trace()</code> function. - - <p>If tracing is enabled and turned on then the penalties from the - previous paragraph apply plus the time required to format each - line of tracing information. There is also an extra call to - H5_trace() for each API function to print the return value. - - <h2>Safety</h2> - - <p>The tracing mechanism is invoked for each API function before - arguments are checked for validity. If bad arguments are passed - to an API function it could result in a segmentation fault. - However, the tracing output is line-buffered so all previous - output will appear. - - <h2>Completeness</h2> - - <p>There are two API functions that don't participate in - tracing. They are <code>H5Eprint()</code> and - <code>H5Eprint_cb()</code> because their participation would - mess up output during automatic error reporting. - - <p>On the other hand, a number of API functions are called during - library initialization and they print tracing information. - - <h2>Implementation</h2> - - <p>For those interested in the implementation here is a - description. Each API function should have a call to one of the - <code>H5TRACE()</code> macros immediately after the - <code>FUNC_ENTER()</code> macro. The first argument is the - return type encoded as a string. The second argument is the - types of all the function arguments encoded as a string. The - remaining arguments are the function arguments. This macro was - designed to be as terse and unobtrousive as possible. - - <p>In order to keep the <code>H5TRACE()</code> calls synchronized - with the source code we've written a perl script which gets - called automatically just before Makefile dependencies are - calculated for the file. However, this only works when one is - using GNU make. To reinstrument the tracing explicitly, invoke - the <code>trace</code> program from the hdf5 bin directory with - the names of the source files that need to be updated. If any - file needs to be modified then a backup is created by appending - a tilde to the file name. - - <p> - <center> - <table border align=center width="100%"> - <caption align=top><b>Explicit Instrumentation</b></caption> - <tr> - <td> - <code><pre> -$ ../bin/trace *.c -H5E.c: in function `H5Ewalk_cb': -H5E.c:336: warning: trace info was not inserted - </pre></code> - </td> - </tr> - </table> - </center> - - <p>Note: The warning message is the result of a comment of the - form <code>/*NO TRACE*/</code> somewhere in the function - body. Tracing information will not be updated or inserted if - such a comment exists. - - <p>Error messages have the same format as a compiler so that they - can be parsed from program development environments like - Emacs. Any function which generates an error will not be - modified. - - - <hr> - <address><a href="mailto:matzke@llnl.gov">Robb Matzke</a></address> -<!-- Created: Wed Jun 17 12:29:12 EDT 1998 --> -<!-- hhmts start --> -Last modified: Wed Jul 8 14:07:23 EDT 1998 -<!-- hhmts end --> - </body> -</html> |