[DTrace-devel] [PATCH 04/12] Aggregations are not data-recording actions

[eugene.loh at oracle.com]

From: Eugene Loh <eugene.loh at oracle.com>

A clause like { @ = count() } should not be data-recording.  The
whole point of aggregations is that we should not have to see output
for every probe firing, even if -q/quiet is turned off.  Nevertheless,
we still have to vet clauses to make sure that, e.g., a clause does
not combine aggregations and speculation.

The reason this problem was not caught earlier is that testing is
typically done in "quiet" mode.

Add a new DT_CLSFLAG_AGGREGATION and split this case off of
DT_CLSFLAG_DATAREC in clause-flag processing.  Add a test for
aggregations that does not use quiet mode.

Signed-off-by: Eugene Loh <eugene.loh at oracle.com>
---
 libdtrace/dt_cg.c                       |  6 +++---
 libdtrace/dtrace.h                      |  1 +
 test/unittest/aggs/tst.count_notquiet.d | 21 +++++++++++++++++++++
 test/unittest/aggs/tst.count_notquiet.r |  6 ++++++
 4 files changed, 31 insertions(+), 3 deletions(-)
 create mode 100644 test/unittest/aggs/tst.count_notquiet.d
 create mode 100644 test/unittest/aggs/tst.count_notquiet.r

diff --git a/libdtrace/dt_cg.c b/libdtrace/dt_cg.c
index db94f8de..f7168ffe 100644
--- a/libdtrace/dt_cg.c
+++ b/libdtrace/dt_cg.c
@@ -833,7 +833,7 @@ dt_cg_clsflags(dt_pcb_t *pcb, dtrace_actkind_t kind, const dt_node_t *dnp)
 		if (*cfp & DT_CLSFLAG_COMMIT)
 			dnerror(dnp, D_COMM_COMM,
 			    "commit( ) may not follow commit( )\n");
-		if (*cfp & DT_CLSFLAG_DATAREC)
+		if (*cfp & (DT_CLSFLAG_DATAREC | DT_CLSFLAG_AGGREGATION))
 			dnerror(dnp, D_COMM_DREC, "commit( ) may "
 			    "not follow data-recording action(s)\n");
 
@@ -850,7 +850,7 @@ dt_cg_clsflags(dt_pcb_t *pcb, dtrace_actkind_t kind, const dt_node_t *dnp)
 			dnerror(dnp, D_SPEC_COMM,
 			    "speculate( ) may not follow commit( )\n");
 
-		if (*cfp & DT_CLSFLAG_DATAREC)
+		if (*cfp & (DT_CLSFLAG_DATAREC | DT_CLSFLAG_AGGREGATION))
 			dnerror(dnp, D_SPEC_DREC, "speculate( ) may "
 			    "not follow data-recording action(s)\n");
 
@@ -866,7 +866,7 @@ dt_cg_clsflags(dt_pcb_t *pcb, dtrace_actkind_t kind, const dt_node_t *dnp)
 			dnerror(dnp, D_AGG_SPEC, "aggregating actions "
 			    "may not follow speculate( )\n");
 
-		*cfp |= DT_CLSFLAG_DATAREC;
+		*cfp |= DT_CLSFLAG_AGGREGATION;
 		return;
 	}
 
diff --git a/libdtrace/dtrace.h b/libdtrace/dtrace.h
index 88c3eeec..ec3730f1 100644
--- a/libdtrace/dtrace.h
+++ b/libdtrace/dtrace.h
@@ -150,6 +150,7 @@ typedef struct dtrace_stmtdesc {
 #define DT_CLSFLAG_COMMIT	4	/* commit */
 #define DT_CLSFLAG_EXIT		8	/* exit */
 #define DT_CLSFLAG_DESTRUCT	16	/* destructive */
+#define DT_CLSFLAG_AGGREGATION	32	/* aggregation */
 
 typedef int dtrace_stmt_f(dtrace_hdl_t *dtp, dtrace_prog_t *pgp,
     dtrace_stmtdesc_t *sdp, void *data);
diff --git a/test/unittest/aggs/tst.count_notquiet.d b/test/unittest/aggs/tst.count_notquiet.d
new file mode 100644
index 00000000..a55e3b41
--- /dev/null
+++ b/test/unittest/aggs/tst.count_notquiet.d
@@ -0,0 +1,21 @@
+/*
+ * Oracle Linux DTrace.
+ * Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
+ * Licensed under the Universal Permissive License v 1.0 as shown at
+ * http://oss.oracle.com/licenses/upl.
+ */
+
+/*
+ * ASSERTION: Aggregations are not data-recording.
+ *
+ * SECTION: Aggregations/Aggregations
+ */
+
+tick-100ms
+{
+	@a = count();
+}
+tick-1005ms
+{
+	exit(0);
+}
diff --git a/test/unittest/aggs/tst.count_notquiet.r b/test/unittest/aggs/tst.count_notquiet.r
new file mode 100644
index 00000000..b6a14daa
--- /dev/null
+++ b/test/unittest/aggs/tst.count_notquiet.r
@@ -0,0 +1,6 @@
+                   FUNCTION:NAME
+                    :tick-1005ms 
+
+               10
+-- @@stderr --
+dtrace: script 'test/unittest/aggs/tst.count_notquiet.d' matched 2 probes
-- 
2.18.4