Merge remote-tracking branch 'stefanha/tracing' into staging

# By Lluís Vilanova (7) and others
# Via Stefan Hajnoczi
* stefanha/tracing:
  vl: add runstate_set tracepoint
  .gitignore: rename trace/generated-tracers.dtrace
  .gitignore: add trace/generated-events.[ch]
  trace: rebuild generated-events.o when configuration changes
  trace: [stderr] Port to generic event information and new control interface
  trace: [simple] Port to generic event information and new control interface
  trace: [default] Port to generic event information and new control interface
  trace: [monitor] Use new event control interface
  trace: Provide a detailed event control interface
  trace: Provide a generic tracing event descriptor
  trace: [tracetool] Explicitly identify public backends

.gitignore

@@ -6,7 +6,9 @@ config-target.*
 trace/generated-tracers.h
 trace/generated-tracers.c
 trace/generated-tracers-dtrace.h
-trace/generated-tracers-dtrace.dtrace
+trace/generated-tracers.dtrace
+trace/generated-events.h
+trace/generated-events.c
 libcacard/trace/generated-tracers.c
 *-timestamp
 *-softmmu

Makefile

@@ -35,6 +35,9 @@ GENERATED_HEADERS = config-host.h qemu-options.def
 GENERATED_HEADERS += qmp-commands.h qapi-types.h qapi-visit.h
 GENERATED_SOURCES += qmp-marshal.c qapi-types.c qapi-visit.c
 
+GENERATED_HEADERS += trace/generated-events.h
+GENERATED_SOURCES += trace/generated-events.c
+
 GENERATED_HEADERS += trace/generated-tracers.h
 ifeq ($(TRACE_BACKEND),dtrace)
 GENERATED_HEADERS += trace/generated-tracers-dtrace.h

docs/tracing.txt

@@ -100,49 +100,37 @@ respectively.  This ensures portability between 32- and 64-bit platforms.
 
 == Generic interface and monitor commands ==
 
-You can programmatically query and control the dynamic state of trace events
-through a backend-agnostic interface:
+You can programmatically query and control the state of trace events through a
+backend-agnostic interface provided by the header "trace/control.h".
 
-* trace_print_events
+Note that some of the backends do not provide an implementation for some parts
+of this interface, in which case QEMU will just print a warning (please refer to
+header "trace/control.h" to see which routines are backend-dependent).
 
-* trace_event_set_state
-  Enables or disables trace events at runtime inside QEMU.
-  The function returns "true" if the state of the event has been successfully
-  changed, or "false" otherwise:
-
-    #include "trace/control.h"
-    
-    trace_event_set_state("virtio_irq", true); /* enable */
-    [...]
-    trace_event_set_state("virtio_irq", false); /* disable */
-
-Note that some of the backends do not provide an implementation for this
-interface, in which case QEMU will just print a warning.
-
-This functionality is also provided through monitor commands:
+The state of events can also be queried and modified through monitor commands:
 
 * info trace-events
   View available trace events and their state.  State 1 means enabled, state 0
   means disabled.
 
 * trace-event NAME on|off
-  Enable/disable a given trace event or a group of events having common prefix
-  through wildcard.
+  Enable/disable a given trace event or a group of events (using wildcards).
 
 The "-trace events=<file>" command line argument can be used to enable the
 events listed in <file> from the very beginning of the program. This file must
 contain one event name per line.
 
-A basic wildcard matching is supported in both the monitor command "trace
--event" and the events list file. That means you can enable/disable the events
-having a common prefix in a batch. For example, virtio-blk trace events could
-be enabled using:
-  trace-event virtio_blk_* on
-
 If a line in the "-trace events=<file>" file begins with a '-', the trace event
 will be disabled instead of enabled.  This is useful when a wildcard was used
 to enable an entire family of events but one noisy event needs to be disabled.
 
+Wildcard matching is supported in both the monitor command "trace-event" and the
+events list file. That means you can enable/disable the events having a common
+prefix in a batch. For example, virtio-blk trace events could be enabled using
+the following monitor command:
+
+    trace-event virtio_blk_* on
+
 == Trace backends ==
 
 The "tracetool" script automates tedious trace event code generation and also
@@ -263,3 +251,7 @@ guard such computations and avoid its compilation when the event is disabled:
         }
         return ptr;
     }
+
+You can check both if the event has been disabled and is dynamically enabled at
+the same time using the 'trace_event_get_state' routine (see header
+"trace/control.h" for more information).

monitor.c

@@ -761,9 +761,18 @@ static void do_trace_event_set_state(Monitor *mon, const QDict *qdict)
 {
     const char *tp_name = qdict_get_str(qdict, "name");
     bool new_state = qdict_get_bool(qdict, "option");
-    int ret = trace_event_set_state(tp_name, new_state);
 
-    if (!ret) {
+    bool found = false;
+    TraceEvent *ev = NULL;
+    while ((ev = trace_event_pattern(tp_name, ev)) != NULL) {
+        found = true;
+        if (!trace_event_get_state_static(ev)) {
+            monitor_printf(mon, "event \"%s\" is not traceable\n", tp_name);
+        } else {
+            trace_event_set_state_dynamic(ev, new_state);
+        }
+    }
+    if (!trace_event_is_pattern(tp_name) && !found) {
         monitor_printf(mon, "unknown event name \"%s\"\n", tp_name);
     }
 }

scripts/tracetool.py

@@ -90,8 +90,8 @@ def main(args):
             arg_format = arg
 
         elif opt == "--list-backends":
-            backends = tracetool.backend.get_list()
-            out(", ".join([ b for b,_ in backends ]))
+            public_backends = tracetool.backend.get_list(only_public = True)
+            out(", ".join([ b for b,_ in public_backends ]))
             sys.exit(0)
         elif opt == "--check-backend":
             check_backend = True

scripts/tracetool/backend/__init__.py

@@ -17,6 +17,16 @@ considered its short description.
 All backends must generate their contents through the 'tracetool.out' routine.
 
 
+Backend attributes
+------------------
+
+========= ====================================================================
+Attribute Description
+========= ====================================================================
+PUBLIC    If exists and is set to 'True', the backend is considered "public".
+========= ====================================================================
+
+
 Backend functions
 -----------------
 
@@ -42,7 +52,7 @@ import os
 import tracetool
 
 
-def get_list():
+def get_list(only_public = False):
     """Get a list of (name, description) pairs."""
     res = [("nop", "Tracing disabled.")]
     modnames = []
@@ -57,6 +67,10 @@ def get_list():
             continue
         module = module[1]
 
+        public = getattr(module, "PUBLIC", False)
+        if only_public and not public:
+            continue
+
         doc = module.__doc__
         if doc is None:
             doc = ""

scripts/tracetool/backend/dtrace.py

@@ -16,6 +16,9 @@ __email__      = "stefanha@linux.vnet.ibm.com"
 from tracetool import out
 
 
+PUBLIC = True
+
+
 PROBEPREFIX = None
 
 def _probeprefix():

scripts/tracetool/backend/events.py

+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+Generic event description.
+
+This is a dummy backend to establish appropriate frontend/backend compatibility
+checks.
+"""
+
+__author__     = "Lluís Vilanova <vilanova@ac.upc.edu>"
+__copyright__  = "Copyright 2012, Lluís Vilanova <vilanova@ac.upc.edu>"
+__license__    = "GPL version 2 or (at your option) any later version"
+
+__maintainer__ = "Stefan Hajnoczi"
+__email__      = "stefanha@linux.vnet.ibm.com"
+
+
+def events_h(events):
+    pass
+
+def events_c(events):
+    pass

scripts/tracetool/backend/simple.py

@@ -15,6 +15,10 @@ __email__      = "stefanha@linux.vnet.ibm.com"
 
 from tracetool import out
 
+
+PUBLIC = True
+
+
 def is_string(arg):
     strtype = ('const char*', 'char*', 'const char *', 'char *')
     if arg.lstrip().startswith(strtype):
@@ -24,17 +28,10 @@ def is_string(arg):
 
 def c(events):
     out('#include "trace.h"',
+        '#include "trace/control.h"',
         '#include "trace/simple.h"',
         '',
-        'TraceEvent trace_list[] = {')
-
-    for e in events:
-        out('{.tp_name = "%(name)s", .state=0},',
-            name = e.name,
-            )
-
-    out('};',
-        '')
+        )
 
     for num, event in enumerate(events):
         out('void trace_%(name)s(%(args)s)',
@@ -59,7 +56,9 @@ def c(events):
 
 
         out('',
-            '    if (!trace_list[%(event_id)s].state) {',
+            '    TraceEvent *eventp = trace_event_id(%(event_id)s);',
+            '    bool _state = trace_event_get_state_dynamic(eventp);',
+            '    if (!_state) {',
             '        return;',
             '    }',
             '',
@@ -102,6 +101,3 @@ def h(events):
             name = event.name,
             args = event.args,
             )
-    out('')
-    out('#define NR_TRACE_EVENTS %d' % len(events))
-    out('extern TraceEvent trace_list[NR_TRACE_EVENTS];')

scripts/tracetool/backend/stderr.py

@@ -16,41 +16,33 @@ __email__      = "stefanha@linux.vnet.ibm.com"
 from tracetool import out
 
 
-def c(events):
-    out('#include "trace.h"',
-        '',
-        'TraceEvent trace_list[] = {')
+PUBLIC = True
 
-    for e in events:
-        out('{.tp_name = "%(name)s", .state=0},',
-            name = e.name,
-            )
 
-    out('};')
+def c(events):
+    pass
 
 def h(events):
     out('#include <stdio.h>',
-        '#include "trace/stderr.h"',
+        '#include "trace/control.h"',
         '',
-        'extern TraceEvent trace_list[];')
+        )
 
-    for num, e in enumerate(events):
+    for e in events:
         argnames = ", ".join(e.args.names())
         if len(e.args) > 0:
             argnames = ", " + argnames
 
         out('static inline void trace_%(name)s(%(args)s)',
             '{',
-            '    if (trace_list[%(event_num)s].state != 0) {',
+            '    bool _state = trace_event_get_state(%(event_id)s);',
+            '    if (_state) {',
             '        fprintf(stderr, "%(name)s " %(fmt)s "\\n" %(argnames)s);',
             '    }',
             '}',
             name = e.name,
             args = e.args,
-            event_num = num,
-            fmt = e.fmt,
+            event_id = "TRACE_" + e.name.upper(),
+            fmt = e.fmt.rstrip("\n"),
             argnames = argnames,
             )
-
-    out('',
-        '#define NR_TRACE_EVENTS %d' % len(events))

scripts/tracetool/backend/ust.py

@@ -16,6 +16,9 @@ __email__      = "stefanha@linux.vnet.ibm.com"
 from tracetool import out
 
 
+PUBLIC = True
+
+
 def c(events):
     out('#include <ust/marker.h>',
         '#undef mutex_lock',

scripts/tracetool/format/events_c.py

+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+Generate .c for event description.
+"""
+
+__author__     = "Lluís Vilanova <vilanova@ac.upc.edu>"
+__copyright__  = "Copyright 2012, Lluís Vilanova <vilanova@ac.upc.edu>"
+__license__    = "GPL version 2 or (at your option) any later version"
+
+__maintainer__ = "Stefan Hajnoczi"
+__email__      = "stefanha@linux.vnet.ibm.com"
+
+
+from tracetool import out
+
+
+def begin(events):
+    out('/* This file is autogenerated by tracetool, do not edit. */',
+        '',
+        '#include "trace.h"',
+        '#include "trace/generated-events.h"',
+        '#include "trace/control.h"',
+        '',
+        )
+
+    out('TraceEvent trace_events[TRACE_EVENT_COUNT] = {')
+
+    for e in events:
+        out('    { .id = %(id)s, .name = \"%(name)s\", .sstate = %(sstate)s, .dstate = 0 },',
+            id = "TRACE_" + e.name.upper(),
+            name = e.name,
+            sstate = "TRACE_%s_ENABLED" % e.name.upper(),
+            )
+
+    out('};',
+        '',
+        )

scripts/tracetool/format/events_h.py

+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+Generate .h for event description.
+"""
+
+__author__     = "Lluís Vilanova <vilanova@ac.upc.edu>"
+__copyright__  = "Copyright 2012, Lluís Vilanova <vilanova@ac.upc.edu>"
+__license__    = "GPL version 2 or (at your option) any later version"
+
+__maintainer__ = "Stefan Hajnoczi"
+__email__      = "stefanha@linux.vnet.ibm.com"
+
+
+from tracetool import out
+
+
+def begin(events):
+    out('/* This file is autogenerated by tracetool, do not edit. */',
+        '',
+        '#ifndef TRACE__GENERATED_EVENTS_H',
+        '#define TRACE__GENERATED_EVENTS_H',
+        '',
+        '#include <stdbool.h>',
+        ''
+        )
+
+    # event identifiers
+    out('typedef enum {')
+
+    for e in events:
+        out('    TRACE_%s,' % e.name.upper())
+
+    out('    TRACE_EVENT_COUNT',
+        '} TraceEventID;',
+        )
+
+    # static state
+    for e in events:
+        if 'disable' in e.properties:
+            enabled = 0
+        else:
+            enabled = 1
+        out('#define TRACE_%s_ENABLED %d' % (e.name.upper(), enabled))
+
+    out('#include "trace/event-internal.h"',
+        '',
+        '#endif  /* TRACE__GENERATED_EVENTS_H */',
+        )

scripts/tracetool/format/h.py

@@ -25,14 +25,7 @@ def begin(events):
         '#include "qemu-common.h"')
 
 def end(events):
-    for e in events:
-        if "disable" in e.properties:
-            enabled = 0
-        else:
-            enabled = 1
-        out('#define TRACE_%s_ENABLED %d' % (e.name.upper(), enabled))
-    out('',
-        '#endif /* TRACE__GENERATED_TRACERS_H */')
+    out('#endif /* TRACE__GENERATED_TRACERS_H */')
 
 def nop(events):
     for e in events:

trace-events

@@ -474,6 +474,7 @@ scsi_request_sense(int target, int lun, int tag) "target %d lun %d tag %d"
 # vl.c
 vm_state_notify(int running, int reason) "running %d reason %d"
 load_file(const char *name, const char *path) "name %s location %s"
+runstate_set(int new_state) "new state %d"
 
 # block/qcow2.c
 qcow2_writev_start_req(void *co, int64_t sector, int nb_sectors) "co %p sector %" PRIx64 " nb_sectors %d"

trace/Makefile.objs

 # -*- mode: makefile -*-
 
 ######################################################################
-# Auto-generated header for tracing routines
+# Auto-generated event descriptions
+
+$(obj)/generated-events.h: $(obj)/generated-events.h-timestamp
+$(obj)/generated-events.h-timestamp: $(SRC_PATH)/trace-events
+	$(call quiet-command,$(TRACETOOL) \
+		--format=events-h \
+		--backend=events \
+		< $< > $@,"  GEN   $(patsubst %-timestamp,%,$@)")
+	@cmp -s $@ $(patsubst %-timestamp,%,$@) || cp $@ $(patsubst %-timestamp,%,$@)
+
+$(obj)/generated-events.c: $(obj)/generated-events.c-timestamp $(BUILD_DIR)/config-host.mak
+$(obj)/generated-events.c-timestamp: $(SRC_PATH)/trace-events
+	$(call quiet-command,$(TRACETOOL) \
+		--format=events-c \
+		--backend=events \
+		< $< > $@,"  GEN   $(patsubst %-timestamp,%,$@)")
+	@cmp -s $@ $(patsubst %-timestamp,%,$@) || cp $@ $(patsubst %-timestamp,%,$@)
+
+util-obj-y += generated-events.o
+
+
+######################################################################
+# Auto-generated tracing routines
 
 $(obj)/generated-tracers.h: $(obj)/generated-tracers.h-timestamp
 	@cmp -s $< $@ || cp $< $@

trace/control-internal.h

+/*
+ * Interface for configuring and controlling the state of tracing events.
+ *
+ * Copyright (C) 2011-2012 Lluís Vilanova <vilanova@ac.upc.edu>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef TRACE__CONTROL_INTERNAL_H
+#define TRACE__CONTROL_INTERNAL_H
+
+#include <string.h>
+
+
+extern TraceEvent trace_events[];
+
+
+static inline TraceEvent *trace_event_id(TraceEventID id)
+{
+    assert(id < trace_event_count());
+    return &trace_events[id];
+}
+
+static inline TraceEventID trace_event_count(void)
+{
+    return TRACE_EVENT_COUNT;
+}
+
+static inline bool trace_event_is_pattern(const char *str)
+{
+    assert(str != NULL);
+    return strchr(str, '*') != NULL;
+}
+
+static inline TraceEventID trace_event_get_id(TraceEvent *ev)
+{
+    assert(ev != NULL);
+    return ev->id;
+}
+
+static inline const char * trace_event_get_name(TraceEvent *ev)
+{
+    assert(ev != NULL);
+    return ev->name;
+}
+
+static inline bool trace_event_get_state_static(TraceEvent *ev)
+{
+    assert(ev != NULL);
+    return ev->sstate;
+}
+
+static inline bool trace_event_get_state_dynamic(TraceEvent *ev)
+{
+    assert(ev != NULL);
+    return ev->dstate;
+}
+
+static inline void trace_event_set_state_dynamic(TraceEvent *ev, bool state)
+{
+    assert(ev != NULL);
+    assert(trace_event_get_state_static(ev));
+    return trace_event_set_state_dynamic_backend(ev, state);
+}
+
+#endif  /* TRACE__CONTROL_INTERNAL_H */

trace/control.c

 /*
  * Interface for configuring and controlling the state of tracing events.
  *
- * Copyright (C) 2011 Lluís Vilanova <vilanova@ac.upc.edu>
+ * Copyright (C) 2011-2012 Lluís Vilanova <vilanova@ac.upc.edu>
  *
- * This work is licensed under the terms of the GNU GPL, version 2.  See
- * the COPYING file in the top-level directory.
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
  */
 
 #include "trace/control.h"
 
 
-void trace_backend_init_events(const char *fname)
+TraceEvent *trace_event_name(const char *name)
+{
+    assert(name != NULL);
+
+    TraceEventID i;
+    for (i = 0; i < trace_event_count(); i++) {
+        TraceEvent *ev = trace_event_id(i);
+        if (strcmp(trace_event_get_name(ev), name) == 0) {
+            return ev;
+        }
+    }
+    return NULL;
+}
+
+static bool pattern_glob(const char *pat, const char *ev)
+{
+    while (*pat != '\0' && *ev != '\0') {
+        if (*pat == *ev) {
+            pat++;
+            ev++;
+        }
+        else if (*pat == '*') {
+            if (pattern_glob(pat, ev+1)) {
+                return true;
+            } else if (pattern_glob(pat+1, ev)) {
+                return true;
+            } else {
+                return false;
+            }
+        } else {
+            return false;
+        }
+    }
+
+    while (*pat == '*') {
+        pat++;
+    }
+
+    if (*pat == '\0' && *ev == '\0') {
+        return true;
+    } else {
+        return false;
+    }
+}
+
+TraceEvent *trace_event_pattern(const char *pat, TraceEvent *ev)
 {
-    int ret;
+    assert(pat != NULL);
 
+    TraceEventID i;
+
+    if (ev == NULL) {
+        i = -1;
+    } else {
+        i = trace_event_get_id(ev);
+    }
+    i++;
+
+    while (i < trace_event_count()) {
+        TraceEvent *res = trace_event_id(i);
+        if (pattern_glob(pat, trace_event_get_name(res))) {
+            return res;
+        }
+        i++;
+    }
+
+    return NULL;
+}
+
+void trace_backend_init_events(const char *fname)
+{
     if (fname == NULL) {
         return;
     }
@@ -32,15 +99,28 @@ void trace_backend_init_events(const char *fname)
             if ('#' == line_buf[0]) { /* skip commented lines */
                 continue;
             }
-            if ('-' == line_buf[0]) {
-                ret = trace_event_set_state(line_buf+1, false);
+            const bool enable = ('-' != line_buf[0]);
+            char *line_ptr = enable ? line_buf : line_buf + 1;
+            if (trace_event_is_pattern(line_ptr)) {
+                TraceEvent *ev = NULL;
+                while ((ev = trace_event_pattern(line_ptr, ev)) != NULL) {
+                    if (trace_event_get_state_static(ev)) {
+                        trace_event_set_state_dynamic(ev, enable);
+                    }
+                }
             } else {
-                ret = trace_event_set_state(line_buf, true);
-            }
-            if (!ret) {
-                fprintf(stderr,
-                        "error: trace event '%s' does not exist\n", line_buf);
-                exit(1);
+                TraceEvent *ev = trace_event_name(line_ptr);
+                if (ev == NULL) {
+                    fprintf(stderr,
+                            "error: trace event '%s' does not exist\n", line_ptr);
+                    exit(1);
+                }
+                if (!trace_event_get_state_static(ev)) {
+                    fprintf(stderr,
+                            "error: trace event '%s' is not traceable\n", line_ptr);
+                    exit(1);
+                }
+                trace_event_set_state_dynamic(ev, enable);
             }
         }
     }

trace/control.h

 /*
  * Interface for configuring and controlling the state of tracing events.
  *
- * Copyright (C) 2011 Lluís Vilanova <vilanova@ac.upc.edu>
+ * Copyright (C) 2011-2012 Lluís Vilanova <vilanova@ac.upc.edu>
  *
- * This work is licensed under the terms of the GNU GPL, version 2.  See
- * the COPYING file in the top-level directory.
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
  */
 
-#ifndef TRACE_CONTROL_H
-#define TRACE_CONTROL_H
+#ifndef TRACE__CONTROL_H
+#define TRACE__CONTROL_H
 
 #include "qemu-common.h"
+#include "trace/generated-events.h"
 
 
-/** Print the state of all events. */
-void trace_print_events(FILE *stream, fprintf_function stream_printf);
-/** Set the state of an event.
+/**
+ * TraceEventID:
+ *
+ * Unique tracing event identifier.
+ *
+ * These are named as 'TRACE_${EVENT_NAME}'.
+ *
+ * See also: "trace/generated-events.h"
+ */
+enum TraceEventID;
+
+/**
+ * trace_event_id:
+ * @id: Event identifier.
+ *
+ * Get an event by its identifier.
+ *
+ * This routine has a constant cost, as opposed to trace_event_name and
+ * trace_event_pattern.
+ *
+ * Pre-conditions: The identifier is valid.
+ *
+ * Returns: pointer to #TraceEvent.
+ *
+ */
+static TraceEvent *trace_event_id(TraceEventID id);
+
+/**
+ * trace_event_name:
+ * @id: Event name.
+ *
+ * Search an event by its name.
+ *
+ * Returns: pointer to #TraceEvent or NULL if not found.
+ */
+TraceEvent *trace_event_name(const char *name);
+
+/**
+ * trace_event_pattern:
+ * @pat: Event name pattern.
+ * @ev: Event to start searching from (not included).
+ *
+ * Get all events with a given name pattern.
+ *
+ * Returns: pointer to #TraceEvent or NULL if not found.
+ */
+TraceEvent *trace_event_pattern(const char *pat, TraceEvent *ev);
+
+/**
+ * trace_event_is_pattern:
+ *
+ * Whether the given string is an event name pattern.
+ */
+static bool trace_event_is_pattern(const char *str);
+
+/**
+ * trace_event_count:
+ *
+ * Return the number of events.
+ */
+static TraceEventID trace_event_count(void);
+
+
+
+/**
+ * trace_event_get_id:
+ *
+ * Get the identifier of an event.
+ */
+static TraceEventID trace_event_get_id(TraceEvent *ev);
+
+/**
+ * trace_event_get_name:
  *
- * @return Whether the state changed.
+ * Get the name of an event.
  */
-bool trace_event_set_state(const char *name, bool state);
+static const char * trace_event_get_name(TraceEvent *ev);
 
+/**
+ * trace_event_get_state:
+ * @id: Event identifier.
+ *
+ * Get the tracing state of an event (both static and dynamic).
+ *
+ * If the event has the disabled property, the check will have no performance
+ * impact.
+ *
+ * As a down side, you must always use an immediate #TraceEventID value.
+ */
+#define trace_event_get_state(id)                       \
+    ((id ##_ENABLED) && trace_event_get_state_dynamic(trace_event_id(id)))
+
+/**
+ * trace_event_get_state_static:
+ * @id: Event identifier.
+ *
+ * Get the static tracing state of an event.
+ *
+ * Use the define 'TRACE_${EVENT_NAME}_ENABLED' for compile-time checks (it will
+ * be set to 1 or 0 according to the presence of the disabled property).
+ */
+static bool trace_event_get_state_static(TraceEvent *ev);
+
+/**
+ * trace_event_get_state_dynamic:
+ *
+ * Get the dynamic tracing state of an event.
+ */
+static bool trace_event_get_state_dynamic(TraceEvent *ev);
+
+/**
+ * trace_event_set_state:
+ *
+ * Set the tracing state of an event (only if possible).
+ */
+#define trace_event_set_state(id, state)                \
+    do {                                                \
+        if ((id ##_ENABLED)) {                          \
+            TraceEvent *_e = trace_event_id(id);        \
+            trace_event_set_state_dynamic(_e, state);   \
+        }                                               \
+    } while (0)
+
+/**
+ * trace_event_set_state_dynamic:
+ *
+ * Set the dynamic tracing state of an event.
+ *
+ * Pre-condition: trace_event_get_state_static(ev) == true
+ */
+static void trace_event_set_state_dynamic(TraceEvent *ev, bool state);
+
+/**
+ * trace_event_set_state_dynamic_backend:
+ *
+ * Warning: This function must be implemented by each tracing backend.
+ */
+void trace_event_set_state_dynamic_backend(TraceEvent *ev, bool state);
+
+
+
+/**
+ * trace_print_events:
+ *
+ * Print the state of all events.
+ *
+ * Warning: This function must be implemented by each tracing backend.
+ */
+void trace_print_events(FILE *stream, fprintf_function stream_printf);
 
-/** Initialize the tracing backend.
+/**
+ * trace_backend_init:
+ * @events: Name of file with events to be enabled at startup; may be NULL.
+ *          Corresponds to commandline option "-trace events=...".
+ * @file:   Name of trace output file; may be NULL.
+ *          Corresponds to commandline option "-trace file=...".
  *
- * @events Name of file with events to be enabled at startup; may be NULL.
- *         Corresponds to commandline option "-trace events=...".
- * @file   Name of trace output file; may be NULL.
- *         Corresponds to commandline option "-trace file=...".
- * @return Whether the backend could be successfully initialized.
+ * Initialize the tracing backend.
+ *
+ * Warning: This function must be implemented by each tracing backend.
+ *
+ * Returns: Whether the backend could be successfully initialized.
  */
 bool trace_backend_init(const char *events, const char *file);
 
-/** Generic function to initialize the state of events.
+/**
+ * trace_backend_init_events:
+ * @fname: Name of file with events to enable; may be NULL.
  *
- * @fname Name of file with events to enable; may be NULL.
+ * Generic function to initialize the state of events.
  */
 void trace_backend_init_events(const char *fname);
 
-#endif  /* TRACE_CONTROL_H */
+
+#include "trace/control-internal.h"
+
+#endif  /* TRACE__CONTROL_H */

trace/default.c

 /*
  * Default implementation for backend initialization from commandline.
  *
- * Copyright (C) 2011 Lluís Vilanova <vilanova@ac.upc.edu>
+ * Copyright (C) 2011-2012 Lluís Vilanova <vilanova@ac.upc.edu>
  *
  * This work is licensed under the terms of the GNU GPL, version 2.  See
  * the COPYING file in the top-level directory.
@@ -18,11 +18,10 @@ void trace_print_events(FILE *stream, fprintf_function stream_printf)
                   "operation not supported with the current backend\n");
 }
 
-bool trace_event_set_state(const char *name, bool state)
+void trace_event_set_state_dynamic_backend(TraceEvent *ev, bool state)
 {
     fprintf(stderr, "warning: "
             "cannot set the state of a trace event with the current backend\n");
-    return false;
 }
 
 bool trace_backend_init(const char *events, const char *file)

trace/event-internal.h

+/*
+ * Interface for configuring and controlling the state of tracing events.
+ *
+ * Copyright (C) 2012 Lluís Vilanova <vilanova@ac.upc.edu>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef TRACE__EVENT_INTERNAL_H
+#define TRACE__EVENT_INTERNAL_H
+
+#include "trace/generated-events.h"
+
+
+/**
+ * TraceEvent:
+ * @id: Unique event identifier.
+ * @name: Event name.
+ * @sstate: Static tracing state.
+ * @dstate: Dynamic tracing state.
+ *
+ * Opaque generic description of a tracing event.
+ */
+typedef struct TraceEvent {
+    TraceEventID id;
+    const char * name;
+    const bool sstate;
+    bool dstate;
+} TraceEvent;
+
+
+#endif  /* TRACE__EVENT_INTERNAL_H */

trace/simple.c

@@ -218,6 +218,7 @@ int trace_record_start(TraceBufferRecord *rec, TraceEventID event, size_t datasi
 {
     unsigned int idx, rec_off, old_idx, new_idx;
     uint32_t rec_len = sizeof(TraceRecord) + datasize;
+    uint64_t event_u64 = event;
     uint64_t timestamp_ns = get_clock();
 
     do {
@@ -235,7 +236,7 @@ int trace_record_start(TraceBufferRecord *rec, TraceEventID event, size_t datasi
     idx = old_idx % TRACE_BUF_LEN;
 
     rec_off = idx;
-    rec_off = write_to_buffer(rec_off, &event, sizeof(event));
+    rec_off = write_to_buffer(rec_off, &event_u64, sizeof(event_u64));
     rec_off = write_to_buffer(rec_off, &timestamp_ns, sizeof(timestamp_ns));
     rec_off = write_to_buffer(rec_off, &rec_len, sizeof(rec_len));
 
@@ -359,38 +360,16 @@ void trace_print_events(FILE *stream, fprintf_function stream_printf)
 {
     unsigned int i;
 
-    for (i = 0; i < NR_TRACE_EVENTS; i++) {
+    for (i = 0; i < trace_event_count(); i++) {
+        TraceEvent *ev = trace_event_id(i);
         stream_printf(stream, "%s [Event ID %u] : state %u\n",
-                      trace_list[i].tp_name, i, trace_list[i].state);
+                      trace_event_get_name(ev), i, trace_event_get_state_dynamic(ev));
     }
 }
 
-bool trace_event_set_state(const char *name, bool state)
+void trace_event_set_state_dynamic_backend(TraceEvent *ev, bool state)
 {
-    unsigned int i;
-    unsigned int len;
-    bool wildcard = false;
-    bool matched = false;
-
-    len = strlen(name);
-    if (len > 0 && name[len - 1] == '*') {
-        wildcard = true;
-        len -= 1;
-    }
-    for (i = 0; i < NR_TRACE_EVENTS; i++) {
-        if (wildcard) {
-            if (!strncmp(trace_list[i].tp_name, name, len)) {
-                trace_list[i].state = state;
-                matched = true;
-            }
-            continue;
-        }
-        if (!strcmp(trace_list[i].tp_name, name)) {
-            trace_list[i].state = state;
-            return true;
-        }
-    }
-    return matched;
+    ev->dstate = state;
 }
 
 /* Helper function to create a thread with signals blocked.  Use glib's

trace/simple.h

@@ -15,12 +15,8 @@
 #include <stdbool.h>
 #include <stdio.h>
 
-typedef uint64_t TraceEventID;
+#include "trace/generated-events.h"
 
-typedef struct {
-    const char *tp_name;
-    bool state;
-} TraceEvent;
 
 void st_print_trace_file_status(FILE *stream, fprintf_function stream_printf);
 void st_set_trace_file_enabled(bool enable);

trace/stderr.c

@@ -4,40 +4,18 @@
 
 void trace_print_events(FILE *stream, fprintf_function stream_printf)
 {
-    unsigned int i;
+    TraceEventID i;
 
-    for (i = 0; i < NR_TRACE_EVENTS; i++) {
+    for (i = 0; i < trace_event_count(); i++) {
+        TraceEvent *ev = trace_event_id(i);
         stream_printf(stream, "%s [Event ID %u] : state %u\n",
-                      trace_list[i].tp_name, i, trace_list[i].state);
+                      trace_event_get_name(ev), i, trace_event_get_state_dynamic(ev));
     }
 }
 
-bool trace_event_set_state(const char *name, bool state)
+void trace_event_set_state_dynamic_backend(TraceEvent *ev, bool state)
 {
-    unsigned int i;
-    unsigned int len;
-    bool wildcard = false;
-    bool matched = false;
-
-    len = strlen(name);
-    if (len > 0 && name[len - 1] == '*') {
-        wildcard = true;
-        len -= 1;
-    }
-    for (i = 0; i < NR_TRACE_EVENTS; i++) {
-        if (wildcard) {
-            if (!strncmp(trace_list[i].tp_name, name, len)) {
-                trace_list[i].state = state;
-                matched = true;
-            }
-            continue;
-        }
-        if (!strcmp(trace_list[i].tp_name, name)) {
-            trace_list[i].state = state;
-            return true;
-        }
-    }
-    return matched;
+    ev->dstate = state;
 }
 
 bool trace_backend_init(const char *events, const char *file)

trace/stderr.h

-#ifndef TRACE_STDERR_H
-#define TRACE_STDERR_H
-
-typedef uint64_t TraceEventID;
-
-typedef struct {
-    const char *tp_name;
-    bool state;
-} TraceEvent;
-
-#endif /* ! TRACE_STDERR_H */

vl.c

@@ -642,7 +642,7 @@ void runstate_set(RunState new_state)
                 RunState_lookup[new_state]);
         abort();
     }
-
+    trace_runstate_set(new_state);
     current_run_state = new_state;
 }