Remove unused ENABLE_LTRACE code.

Although I'm not too familiar with SystemTap, I'm pretty sure that recent
versions can do user space tracing better. I don't think anyone is using
these hacks anymore, so remove them.

src/backend/cdb/cdbvars.c

@@ -280,9 +280,6 @@ int			gp_hashjoin_bloomfilter = 0;
 
 /* Analyzing aid */
 int			gp_motion_slice_noop = 0;
-#ifdef ENABLE_LTRACE
-int			gp_ltrace_flag = 0;
-#endif
 
 /* Greenplum Database Experimental Feature GUCs */
 int			gp_distinct_grouping_sets_threshold = 32;

src/backend/utils/error/Makefile

@@ -12,6 +12,6 @@ subdir = src/backend/utils/error
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
-OBJS = assert.o debugbreak.o debugutils.o elog.o faultinject.o pg_ltrace.o
+OBJS = assert.o debugbreak.o debugutils.o elog.o faultinject.o
 
 include $(top_srcdir)/src/backend/common.mk

src/backend/utils/error/pg_ltrace.c

-/*-------------------------------------------------------------------------
- *
- * pg_ltrace.c
- *	  Poor linux's tracing facility.
- *
- * Portions Copyright (c) 2008, Greenplum Inc.
- * Portions Copyright (c) 2012-Present Pivotal Software, Inc.
- *
- *
- * IDENTIFICATION
- *	    src/backend/utils/error/pg_ltrace.c
- *-------------------------------------------------------------------------
- */
-
-#include <pg_config.h>
-#ifdef ENABLE_LTRACE
-#include <sys/types.h>
-
-#include <unistd.h>
-#include <pg_trace.h>
-#include <stdio.h>
-
-extern int gp_ltrace_flag;
-
-struct pg_trace_data_t
-{
-	long val[9];
-};
-
-/* 
- * Poor linux tracing facility.
- *
- * Unlike dtrace, linux tracing (SystemTap) at this moment
- * does not support user space tracing.  We use the following
- * HACK to get some tracing.
- *
- * The write is strange.  Postgres will redirect fd 0 (stdin) to 
- * read from /dev/null.  We are writing to stdin, a string of 0 bytes.
- * it will fail, as stdin is readonly, but, it is still a system call.
- * In system tap, we can catch at syscall.write and test $fd == 0 and 
- * $count == 0.  The constructed buffer can be accessed by $buf.
- *
- * Note that the $fd = 0 and $count = 0 hack is kind of "Needed".  
- * If the fd is not valid, then actually the systemtap syscalls tapset
- * will not catch it.  Count set to 0 is safe.
- *
- * NOTE: At this moment, SystemTap cannot even display user stack.
- * if we really want the stack, we can construct the stack using backtrace()
- * and put the string as the str arg.
- * 
- * filename and funcname can be used a quick dirty depth 1 stack.
- *
- * The stp script need to match the t.val layout.  Right now, 
- * 	0 	family
- *	1 	filename
- *	2 	funcname
- *	3 	line number
- *	4-9 	5 args
- */
-
-#if 0 
----------------------  BEGIN EXAMPLE STP ---------------------------------
-#! /usr/bin/env stap
-
-/* 
- * Example stap.  The stp must be run as root because it uses embeded C.
- *
- * sudo stap -g my.stp
- */
-
-function pgtrace_decode_val:long(pgtrace_data:long, fieldnum:long)
-%{
-	struct pg_trace_data_t {
-		long iv[9];
-	};
-
-	struct pg_trace_data_t *p = (struct pg_trace_data_t *) (long) THIS->pgtrace_data;
-	if(p && THIS->fieldnum >= 0 && THIS->fieldnum < 9) 
-		THIS->__retvalue = kread(&(p->iv[THIS->fieldnum]));
-	else
-		THIS->__retvalue = 0;
-
-	CATCH_DEREF_FAULT();
-%}
-
-probe syscall.write {
-	/* We have $fd, $count, and $buf.  Need to access $buf with user_string($buf) */
-	if($fd == 0 && $count == 0)
-	{
-		printf("PGTrace family %d, file %s, func %s line %d: args: %d, %d, %d, %d, %d\n", 
-				pgtrace_decode_val($buf, 0),
-				user_string(pgtrace_decode_val($buf, 1)),
-				user_string(pgtrace_decode_val($buf, 2)),
-				pgtrace_decode_val($buf, 3),
-				pgtrace_decode_val($buf, 4),
-				pgtrace_decode_val($buf, 5),
-				pgtrace_decode_val($buf, 6),
-				pgtrace_decode_val($buf, 7),
-				pgtrace_decode_val($buf, 8)
-		      )
-	}
-}	
---------------------- END EXAMPLE STP -----------------------------------------
-#endif
-
-void LTRACE_PROBE_FIRE(long family, 
-		const char *filename, const char *funcname, long line,
-		long i1, long i2, long i3, long i4, long i5
-		)
-{
-	if(gp_ltrace_flag)
-	{
-		struct pg_trace_data_t t;
-		t.val[0] = family;
-		t.val[1] = (long) filename;
-		t.val[2] = (long) funcname;
-		t.val[3] = line;
-		t.val[4] = i1;
-		t.val[5] = i2;
-		t.val[6] = i3;
-		t.val[7] = i4;
-		t.val[8] = i5;
-
-		write(0, (char *) &t, 0);
-	}
-}
-#endif

src/backend/utils/misc/guc_gp.c

@@ -4226,18 +4226,6 @@ struct config_int ConfigureNamesInt_gp[] =
 		0, 0, INT_MAX, NULL, NULL
 	},
 
-#ifdef ENABLE_LTRACE
-	{
-		{"gp_ltrace_flag", PGC_USERSET, GP_ARRAY_TUNING,
-			gettext_noop("Linux Tracing flag"),
-			gettext_noop("Linux Tracing flag"),
-			GUC_NOT_IN_SAMPLE | GUC_NO_SHOW_ALL | GUC_GPDB_ADDOPT
-		},
-		&gp_ltrace_flag,
-		0, 0, INT_MAX, NULL, NULL
-	},
-#endif
-
 	{
 		{"gp_reject_percent_threshold", PGC_USERSET, GP_ERROR_HANDLING,
 			gettext_noop("Reject limit in percent starts calculating after this number of rows processed"),

src/include/cdb/cdbvars.h

@@ -893,9 +893,6 @@ extern double	gp_statistics_sampling_threshold;
 
 /* Analyze tools */
 extern int gp_motion_slice_noop;
-#ifdef ENABLE_LTRACE
-extern int gp_ltrace_flag;
-#endif
 
 /* Disable setting of hint-bits while reading db pages */
 extern bool gp_disable_tuple_hints;

src/include/pg_trace.h

@@ -13,7 +13,6 @@
 #define PG_TRACE_H
 
 #ifdef ENABLE_DTRACE
-#define PGTRACE_ENABLED
 
 #include <sys/sdt.h>
 
@@ -37,78 +36,8 @@
 	DTRACE_PROBE4(postgresql, name, arg1, arg2, arg3, arg4)
 #define PG_TRACE5(name, arg1, arg2, arg3, arg4, arg5) \
 	DTRACE_PROBE5(postgresql, name, arg1, arg2, arg3, arg4, arg5)
+#else							/* not ENABLE_DTRACE */
 
-#define LTRACE_PROBE(family, fn, fc, l, i1, i2, i3, i4, i5)
-
-#else
-#ifdef ENABLE_LTRACE
-#define PGTRACE_ENABLED
-enum 
-{
-	/* Postgres dtrace family, 1 to 999,999 */
-	/* See src/backend/utils/probes.d */
-	transaction__start  = 1, 
-	transaction__commit,
-	transaction__abort,
-	lwlock__acquire,
-	lwlock__release,
-	lwlock__startwait,
-	lwlock__endwait,
-	lwlock__condacquire,
-	lwlock__condacquire__fail,
-	lock__startwait,
-	lock__endwait,
-
-	memctxt__alloc,
-	memctxt__free,
-	memctxt__realloc,
-
-	execprocnode__enter,
-	execprocnode__exit,
-
-	tuplesort__begin,
-	tuplesort__end,
-	tuplesort__perform__sort,
-	tuplesort__mergeonerun,
-	tuplesort__dumptuples,
-	tuplesort__switch__external,
-
-	/* Internal test and debug use */
-	LTR_DEBUG_START = 1000000,
-
-	/* Internal test and debug, very verbose */
-	LTR_DEBUG_VERBOSE = 2000000,
-};
-
-extern int gp_ltrace_flag;
-extern void LTRACE_PROBE_FIRE(long family, 
-	const char *filen, const char *func, long line,
-	long i1, long i2, long i3, long i4, long i5
-	);
-static inline void LTRACE_PROBE(long family, 
-	const char *filen, const char *func, long line,
-	long i1, long i2, long i3, long i4, long i5
-	)
-{
-	if(family < gp_ltrace_flag)
-		LTRACE_PROBE_FIRE(family, filen, func, line,
-				i1, i2, i3, i4, i5);
-}
-
-#define PG_TRACE(name) \
-	LTRACE_PROBE(name, __FILE__, PG_FUNCNAME_MACRO, __LINE__, 0, 0, 0, 0, 0)
-#define PG_TRACE1(name, arg1) \
-	LTRACE_PROBE(name, __FILE__, PG_FUNCNAME_MACRO, __LINE__, arg1, 0, 0, 0, 0)
-#define PG_TRACE2(name, arg1, arg2) \
-	LTRACE_PROBE(name, __FILE__, PG_FUNCNAME_MACRO, __LINE__, arg1, arg2, 0, 0, 0)
-#define PG_TRACE3(name, arg1, arg2, arg3) \
-	LTRACE_PROBE(name, __FILE__, PG_FUNCNAME_MACRO, __LINE__, arg1, arg2, arg3, 0, 0)
-#define PG_TRACE4(name, arg1, arg2, arg3, arg4) \
-	LTRACE_PROBE(name, __FILE__, PG_FUNCNAME_MACRO, __LINE__, arg1, arg2, arg3, arg4, 0)
-#define PG_TRACE5(name, arg1, arg2, arg3, arg4, arg5) \
-	LTRACE_PROBE(name, __FILE__, PG_FUNCNAME_MACRO, __LINE__, arg1, arg2, arg3, arg4, arg5)
-
-#else   /* No tracing */
 /*
  * Unless DTrace is explicitly enabled with --enable-dtrace, the PG_TRACE
  * macros will expand to no-ops.
@@ -120,8 +49,6 @@ static inline void LTRACE_PROBE(long family,
 #define PG_TRACE3(name, arg1, arg2, arg3)
 #define PG_TRACE4(name, arg1, arg2, arg3, arg4)
 #define PG_TRACE5(name, arg1, arg2, arg3, arg4, arg5)
-#define LTRACE_PROBE(family, fn, fc, l, i1, i2, i3, i4, i5)
-
-#endif   /* not ENABLE_LTRACE */
 #endif   /* not ENABLE_DTRACE */
+
 #endif   /* PG_TRACE_H */