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<title>OCI8 and DTrace Dynamic Tracing</title>
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</div><hr /><div id="oci8.dtrace" class="chapter">
<h1>OCI8 and DTrace Dynamic Tracing</h1>
<div class="section">
<p class="para">
OCI8 2.0 introduced static DTrace probes that can be used on
operating systems that support DTrace.
See <a href="features.dtrace.html" class="link">DTrace Dynamic Tracing</a>
for an overview of PHP and DTrace.
</p>
</div>
<div class="section">
<h2 class="title">Installing OCI8 with DTrace Support</h2>
<p class="para">
To enable DTrace support in PHP OCI8, build OCI8 as a shared
extension after setting <em>PHP_DTRACE</em>.
</p>
<p class="para">
<div class="informalexample">
<div class="example-contents screen">
<div class="cdata"><pre>
$ export PHP_DTRACE=yes
$ pecl install oci8
</pre></div>
</div>
</div>
</p>
<p class="para">
Edit php.ini,
set <a href="ini.core.html#ini.extension-dir" class="link">extension_dir</a> to the
directory with the created <var class="filename">oci8.so</var> and also
enable the extension by adding:
</p>
<p class="para">
<div class="informalexample">
<div class="example-contents screen">
<div class="cdata"><pre>
extension=oci8.so
</pre></div>
</div>
</div>
</p>
<p class="para">
If you install PHP OCI8 2.0 from PECL using <var class="filename">phpize</var> and
<var class="filename">configure</var> (instead
of <var class="filename">pecl</var>), you will still need to set
<em>PHP_DTRACE=yes</em>. This is because
the <em>--enable-dtrace</em> option will be ignored by the
limited <var class="filename">configure</var> script of a PECL bundle.
</p>
<p class="para">
See <a href="install.pecl.html" class="link">Installation of PECL
extensions</a> for general PECL installation instructions.
</p>
</div>
<div class="section">
<h2 class="title">DTrace Static Probes in PHP OCI8</h2>
<table class="doctable table">
<caption><strong>The following static probes are available in PHP OCI8</strong></caption>
<thead>
<tr>
<th>Probe Name</th>
<th>Probe Description</th>
<th>Probe Arguments</th>
</tr>
</thead>
<tbody class="tbody">
<tr>
<td><em>oci8-connect-entry</em></td>
<td>Initiated by oci_connect(), oci_pconnect() and oci_new_connect(). Fires before database connection is established.</td>
<td>char *<var class="varname"><var class="varname">username</var></var>, char *<var class="varname"><var class="varname">dbname</var></var>, char *<var class="varname"><var class="varname">charset</var></var>, long <var class="varname"><var class="varname">session_mode</var></var>, int <var class="varname"><var class="varname">persistent</var></var>, int <var class="varname"><var class="varname">exclusive</var></var></td>
</tr>
<tr>
<td><em>oci8-connect-return</em></td>
<td>Fires at the end of connection.</td>
<td>void *<var class="varname"><var class="varname">connection</var></var></td>
</tr>
<tr>
<td><em>oci8-check-connection</em></td>
<td>Fires if an Oracle error might have caused the connection to become invalid.</td>
<td>void *<var class="varname"><var class="varname">connection</var></var>, char *<var class="varname"><var class="varname">client_id</var></var>, int <var class="varname"><var class="varname">is_open</var></var>, long <var class="varname"><var class="varname">errcode</var></var>, unsigned long <var class="varname"><var class="varname">server_status</var></var></td>
</tr>
<tr>
<td><em>oci8-sqltext</em></td>
<td>Fires when oci_parse() is executed.</td>
<td>void *<var class="varname"><var class="varname">connection</var></var>, char *<var class="varname"><var class="varname">client_id</var></var>, void *<var class="varname"><var class="varname">statement</var></var>, char *<var class="varname"><var class="varname">sql</var></var></td>
</tr>
<tr>
<td><em>oci8-connection-close</em></td>
<td>Fires when the connection to the database is completely destroyed.</td>
<td>void *<var class="varname"><var class="varname">connection</var></var></td>
</tr>
<tr>
<td><em>oci8-error</em></td>
<td>Fires if an Oracle error occurs.</td>
<td>int <var class="varname"><var class="varname">status</var></var>, long <var class="varname"><var class="varname">errcode</var></var></td>
</tr>
<tr>
<td><em>oci8-execute-mode</em></td>
<td>Fires at <span class="function"><a href="function.oci-execute.html" class="function">oci_execute()</a></span> to show the execution mode.</td>
<td>void *<var class="varname"><var class="varname">connection</var></var>, char *<var class="varname"><var class="varname">client_id</var></var>, void *<var class="varname"><var class="varname">statement</var></var>, unsigned int <var class="varname"><var class="varname">mode</var></var></td>
</tr>
</tbody>
</table>
<p class="para">
These probes are useful for tracing OCI8 scripts.
</p>
<p class="para">
The <var class="varname"><var class="varname">connection</var></var> and <var class="varname"><var class="varname">statement</var></var>
are the pointers to internal structures used for tracking PHP
connections and executed statements.
</p>
<p class="para">
The <var class="varname"><var class="varname">client_id</var></var> is the value set
by <span class="function"><a href="function.oci-set-client-identifier.html" class="function">oci_set_client_identifier()</a></span>.
</p>
<p class="para">
</p>
<p class="para">
</p>
<p class="para">
</p>
<p class="para">
Core PHP also has static probes.
See <a href="features.dtrace.dtrace.html#features.dtrace.static-probes" class="link">DTrace Static
Probes in Core PHP</a>.
</p>
<table class="doctable table">
<caption><strong>Internal Debugging DTrace Probes in OCI8</strong></caption>
<thead>
<tr>
<th>Probe Name</th>
</tr>
</thead>
<tbody class="tbody">
<tr>
<td><em>oci8-connect-expiry</em></td>
</tr>
<tr>
<td><em>oci8-connect-lookup</em></td>
</tr>
<tr>
<td><em>oci8-connect-p-dtor-close</em></td>
</tr>
<tr>
<td><em>oci8-connect-p-dtor-release</em></td>
</tr>
<tr>
<td><em>oci8-connect-type</em></td>
</tr>
<tr>
<td><em>oci8-sesspool-create</em></td>
</tr>
<tr>
<td><em>oci8-sesspool-stats</em></td>
</tr>
<tr>
<td><em>oci8-sesspool-type</em></td>
</tr>
</tbody>
</table>
<p class="para">
These probes are useful for OCI8 maintainers. Refer to the OCI8 source code for arguments and to see when the will fire.
</p>
</div>
<div class="section">
<h2 class="title">Listing DTrace Static Probes in PHP OCI8</h2>
<p class="para">
To list available probes, start a PHP process and then run:
<div class="informalexample">
<div class="example-contents">
<div class="cdata"><pre>
# dtrace -l
</pre></div>
</div>
</div>
</p>
<p class="para">
The output will be similar to:
<div class="informalexample">
<div class="example-contents">
<div class="cdata"><pre>
ID PROVIDER MODULE FUNCTION NAME
[ . . . ]
17 phpoci22116 oci8.so php_oci_dtrace_check_connection oci8-check-connection
18 phpoci22116 oci8.so php_oci_do_connect oci8-connect-entry
19 phpoci22116 oci8.so php_oci_persistent_helper oci8-connect-expiry
20 phpoci22116 oci8.so php_oci_do_connect_ex oci8-connect-lookup
21 phpoci22116 oci8.so php_oci_pconnection_list_np_dtor oci8-connect-p-dtor-close
22 phpoci22116 oci8.so php_oci_pconnection_list_np_dtor oci8-connect-p-dtor-release
23 phpoci22116 oci8.so php_oci_do_connect oci8-connect-return
24 phpoci22116 oci8.so php_oci_do_connect_ex oci8-connect-type
25 phpoci22116 oci8.so php_oci_connection_close oci8-connection-close
26 phpoci22116 oci8.so php_oci_error oci8-error
27 phpoci22116 oci8.so php_oci_statement_execute oci8-execute-mode
28 phpoci22116 oci8.so php_oci_create_spool oci8-sesspool-create
29 phpoci22116 oci8.so php_oci_create_session oci8-sesspool-stats
30 phpoci22116 oci8.so php_oci_create_session oci8-sesspool-type
31 phpoci22116 oci8.so php_oci_statement_create oci8-sqltext
</pre></div>
</div>
</div>
</p>
<p class="para">
The Provider column values consist of <em>phpoci</em> and
the process id of the currently running PHP process.
</p>
<p class="para">
The Function column refers to PHP's internal C implementation
function names where each provider is located.
</p>
<p class="para">
If a PHP process is not running, then no PHP probes will be shown.
</p>
</div>
<div class="section">
<h2 class="title">DTrace with PHP OCI8 Example</h2>
<p class="para">
This example shows the basics of the DTrace D scripting language.
<div class="example" id="example-1942">
<p><strong>Example #1 <var class="filename">user_oci8_probes.d</var> for tracing all user-level PHP OCI8 Static Probes with DTrace</strong></p>
<div class="example-contents">
<div class="cdata"><pre>
#!/usr/sbin/dtrace -Zs
#pragma D option quiet
php*:::oci8-connect-entry
{
printf("%lld: PHP connect-entry\n", walltimestamp);
printf(" credentials=\"%s@%s\"\n", arg0 ? copyinstr(arg0) : "", arg1 ? copyinstr(arg1) : "");
printf(" charset=\"%s\"\n", arg2 ? copyinstr(arg2) : "");
printf(" session_mode=%ld\n", (long)arg3);
printf(" persistent=%d\n", (int)arg4);
printf(" exclusive=%d\n", (int)arg5);
}
php*:::oci8-connect-return
{
printf("%lld: PHP oci8-connect-return\n", walltimestamp);
printf(" connection=0x%p\n", (void *)arg0);
}
php*:::oci8-connection-close
{
printf("%lld: PHP oci8-connect-close\n", walltimestamp);
printf(" connection=0x%p\n", (void *)arg0);
}
php*:::oci8-error
{
printf("%lld: PHP oci8-error\n", walltimestamp);
printf(" status=%d\n", (int)arg0);
printf(" errcode=%ld\n", (long)arg1);
}
php*:::oci8-check-connection
{
printf("%lld: PHP oci8-check-connection\n", walltimestamp);
printf(" connection=0x%p\n", (void *)arg0);
printf(" client_id=\"%s\"\n", arg1 ? copyinstr(arg1) : "");
printf(" is_open=%d\n", arg2);
printf(" errcode=%ld\n", (long)arg3);
printf(" server_status=%lu\n", (unsigned long)arg4);
}
php*:::oci8-sqltext
{
printf("%lld: PHP oci8-sqltext\n", walltimestamp);
printf(" connection=0x%p\n", (void *)arg0);
printf(" client_id=\"%s\"\n", arg1 ? copyinstr(arg1) : "");
printf(" statement=0x%p\n", (void *)arg2);
printf(" sql=\"%s\"\n", arg3 ? copyinstr(arg3) : "");
}
php*:::oci8-execute-mode
{
printf("%lld: PHP oci8-execute-mode\n", walltimestamp);
printf(" connection=0x%p\n", (void *)arg0);
printf(" client_id=\"%s\"\n", arg1 ? copyinstr(arg1) : "");
printf(" statement=0x%p\n", (void *)arg2);
printf(" mode=0x%x\n", arg3);
}
</pre></div>
</div>
</div>
</p>
<p class="para">
This script uses the <em>-Z</em> option to
<var class="filename">dtrace</var>, allowing it to be run when there is no
PHP process executing. If this option were omitted the script
would immediately terminate when no PHP executable was running
because it knows none of the probes to be monitored are in
existence.
</p>
<p class="para">
On multi-CPU machines the probe ordering might not appear to be
sequential. This depends on which CPU was processing the probes,
and how threads migrate across CPUs. Displaying probe time stamps
helps reduce confusion.
</p>
<p class="para">
The script traces all user-level PHP OCI8 static probe points
throughout the duration of a running PHP script. Run the D script:
<div class="informalexample">
<div class="example-contents">
<div class="cdata"><pre>
# ./user_oci8_probes.d
</pre></div>
</div>
</div>
</p>
<p class="para">
Run a PHP script or application. The monitoring D script will
output each probe's arguments as it fires. For example, a simple
PHP script that queries a table might produce the following trace
output:
<div class="informalexample">
<div class="example-contents">
<div class="cdata"><pre>
1381794982092854582: PHP connect-entry
credentials="hr@localhost/pdborcl"
charset=""
session_mode=0
persistent=0
exclusive=0
1381794982183158766: PHP oci8-connect-return
connection=0x7f4a7907bfb8
1381794982183594576: PHP oci8-sqltext
connection=0x7f4a7907bfb8
client_id="Chris"
statement=0x7f4a7907c2a0
sql="select * from employees"
1381794982183783706: PHP oci8-execute-mode
connection=0x7f4a7907bfb8
client_id="Chris"
statement=0x7f4a7907c2a0
mode=0x20
1381794982444344390: PHP oci8-connect-close
connection=0x7f4a7907bfb8
</pre></div>
</div>
</div>
</p>
<p class="para">
When monitoring is complete, the D script can be terminated with a
<em>^C</em>.
</p>
</div>
<div class="section">
<h2 class="title">See Also</h2>
<ul class="simplelist">
<li class="member"><a href="features.dtrace.html" class="link">DTrace Dynamic Tracing</a></li>
</ul>
</div>
</div>
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