trace: [tracetool] Minimize the amount of per-backend code

Backends now only contain the essential backend-specific code, and most of the work is moved to frontend code.

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

7 files changed, 153 insertions, 313 deletions

diff --git a/scripts/tracetool/backend/__init__.py b/scripts/tracetool/backend/__init__.py
index 88f94fd..5e36f04 100644
--- a/scripts/tracetool/backend/__init__.py
+++ b/scripts/tracetool/backend/__init__.py
@@ -30,17 +30,24 @@ PUBLIC    If exists and is set to 'True', the backend is considered "public".
 Backend functions
 -----------------
 
-======== =======================================================================
-Function Description
-======== =======================================================================
-<format> Called to generate the format- and backend-specific code for each of
-         the specified events. If the function does not exist, the backend is
-         considered not compatible with the given format.
-======== =======================================================================
+All the following functions are optional, and no output will be generated if
+they do not exist.
+
+=============================== ==============================================
+Function                        Description
+=============================== ==============================================
+generate_<format>_begin(events) Generate backend- and format-specific file
+                                header contents.
+generate_<format>_end(events)   Generate backend- and format-specific file
+                                footer contents.
+generate_<format>(event)        Generate backend- and format-specific contents
+                                for the given event.
+=============================== ==============================================
+
 """
 
 __author__     = "Lluís Vilanova <vilanova@ac.upc.edu>"
-__copyright__  = "Copyright 2012, Lluís Vilanova <vilanova@ac.upc.edu>"
+__copyright__  = "Copyright 2012-2014, Lluís Vilanova <vilanova@ac.upc.edu>"
 __license__    = "GPL version 2 or (at your option) any later version"
 
 __maintainer__ = "Stefan Hajnoczi"
@@ -91,39 +98,24 @@ def exists(name):
     return tracetool.try_import("tracetool.backend." + name)[1]
 
 
-def compatible(backend, format):
-    """Whether a backend is compatible with the given format."""
-    if not exists(backend):
-        raise ValueError("unknown backend: %s" % backend)
-
-    backend = backend.replace("-", "_")
-    format = format.replace("-", "_")
-
-    if backend == "nop":
-        return True
-    else:
-        func = tracetool.try_import("tracetool.backend." + backend,
-                                    format, None)[1]
-        return func is not None
-
-
-def _empty(events):
-    pass
+class Wrapper:
+    def __init__(self, backend, format):
+        self._backend = backend.replace("-", "_")
+        self._format = format.replace("-", "_")
+        assert exists(self._backend)
+        assert tracetool.format.exists(self._format)
 
-def generate(backend, format, events):
-    """Generate the per-event output for the given (backend, format) pair."""
-    if not compatible(backend, format):
-        raise ValueError("backend '%s' not compatible with format '%s'" %
-                         (backend, format))
+    def _run_function(self, name, *args, **kwargs):
+        func = tracetool.try_import("tracetool.backend." + self._backend,
+                                    name % self._format, None)[1]
+        if func is not None:
+            func(*args, **kwargs)
 
-    backend = backend.replace("-", "_")
-    format = format.replace("-", "_")
+    def generate_begin(self, events):
+        self._run_function("generate_%s_begin", events)
 
-    if backend == "nop":
-        func = tracetool.try_import("tracetool.format." + format,
-                                    "nop", _empty)[1]
-    else:
-        func = tracetool.try_import("tracetool.backend." + backend,
-                                    format, None)[1]
+    def generate(self, event):
+        self._run_function("generate_%s", event)
 
-    func(events)
+    def generate_end(self, events):
+        self._run_function("generate_%s_end", events)
diff --git a/scripts/tracetool/backend/dtrace.py b/scripts/tracetool/backend/dtrace.py
index 3c369c4..fabfe99 100644
--- a/scripts/tracetool/backend/dtrace.py
+++ b/scripts/tracetool/backend/dtrace.py
@@ -21,7 +21,7 @@ PUBLIC = True
 
 PROBEPREFIX = None
 
-def _probeprefix():
+def probeprefix():
     if PROBEPREFIX is None:
         raise ValueError("you must set PROBEPREFIX")
     return PROBEPREFIX
@@ -29,81 +29,18 @@ def _probeprefix():
 
 BINARY = None
 
-def _binary():
+def binary():
     if BINARY is None:
         raise ValueError("you must set BINARY")
     return BINARY
 
 
-def c(events):
-    pass
-
-
-def h(events):
+def generate_h_begin(events):
     out('#include "trace/generated-tracers-dtrace.h"',
         '')
 
-    for e in events:
-        out('static inline void %(api)s(%(args)s) {',
-            '    QEMU_%(uppername)s(%(argnames)s);',
-            '}',
-            api = e.api(),
-            args = e.args,
-            uppername = e.name.upper(),
-            argnames = ", ".join(e.args.names()),
-            )
-
-
-def d(events):
-    out('provider qemu {')
-
-    for e in events:
-        args = str(e.args)
-
-        # DTrace provider syntax expects foo() for empty
-        # params, not foo(void)
-        if args == 'void':
-            args = ''
-
-        # Define prototype for probe arguments
-        out('',
-            'probe %(name)s(%(args)s);',
-            name = e.name,
-            args = args,
-            )
-
-    out('',
-        '};')
-
-
-# Technically 'self' is not used by systemtap yet, but
-# they recommended we keep it in the reserved list anyway
-RESERVED_WORDS = (
-    'break', 'catch', 'continue', 'delete', 'else', 'for',
-    'foreach', 'function', 'global', 'if', 'in', 'limit',
-    'long', 'next', 'probe', 'return', 'self', 'string',
-    'try', 'while'
-    )
-
-def stap(events):
-    for e in events:
-        # Define prototype for probe arguments
-        out('probe %(probeprefix)s.%(name)s = process("%(binary)s").mark("%(name)s")',
-            '{',
-            probeprefix = _probeprefix(),
-            name = e.name,
-            binary = _binary(),
-            )
-
-        i = 1
-        if len(e.args) > 0:
-            for name in e.args.names():
-                # Append underscore to reserved keywords
-                if name in RESERVED_WORDS:
-                    name += '_'
-                out('  %s = $arg%d;' % (name, i))
-                i += 1
-
-        out('}')
-
-    out()
+
+def generate_h(event):
+    out('    QEMU_%(uppername)s(%(argnames)s);',
+        uppername=event.name.upper(),
+        argnames=", ".join(event.args.names()))
diff --git a/scripts/tracetool/backend/events.py b/scripts/tracetool/backend/events.py
deleted file mode 100644
index 5afce3e..0000000
--- a/scripts/tracetool/backend/events.py
+++ /dev/null
@@ -1,23 +0,0 @@
-#!/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
diff --git a/scripts/tracetool/backend/ftrace.py b/scripts/tracetool/backend/ftrace.py
index 888c361..d798c71 100644
--- a/scripts/tracetool/backend/ftrace.py
+++ b/scripts/tracetool/backend/ftrace.py
@@ -19,36 +19,30 @@ from tracetool import out
 PUBLIC = True
 
 
-def c(events):
-    pass
-
-def h(events):
+def generate_h_begin(events):
     out('#include "trace/ftrace.h"',
         '#include "trace/control.h"',
-        '',
-        )
-
-    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)',
-            '{',
-            '    char ftrace_buf[MAX_TRACE_STRLEN];',
-            '    int unused __attribute__ ((unused));',
-            '    int trlen;',
-            '    bool _state = trace_event_get_state(%(event_id)s);',
-            '    if (_state) {',
-            '        trlen = snprintf(ftrace_buf, MAX_TRACE_STRLEN,',
-            '                         "%(name)s " %(fmt)s "\\n" %(argnames)s);',
-            '        trlen = MIN(trlen, MAX_TRACE_STRLEN - 1);',
-            '        unused = write(trace_marker_fd, ftrace_buf, trlen);',
-            '    }',
-            '}',
-            name = e.name,
-            args = e.args,
-            event_id = "TRACE_" + e.name.upper(),
-            fmt = e.fmt.rstrip("\n"),
-            argnames = argnames,
-            )
+        '')
+
+
+def generate_h(event):
+    argnames = ", ".join(event.args.names())
+    if len(event.args) > 0:
+        argnames = ", " + argnames
+
+    out('    {',
+        '        char ftrace_buf[MAX_TRACE_STRLEN];',
+        '        int unused __attribute__ ((unused));',
+        '        int trlen;',
+        '        if (trace_event_get_state(%(event_id)s)) {',
+        '            trlen = snprintf(ftrace_buf, MAX_TRACE_STRLEN,',
+        '                             "%(name)s " %(fmt)s "\\n" %(argnames)s);',
+        '            trlen = MIN(trlen, MAX_TRACE_STRLEN - 1);',
+        '            unused = write(trace_marker_fd, ftrace_buf, trlen);',
+        '        }',
+        '    }',
+        name=event.name,
+        args=event.args,
+        event_id="TRACE_" + event.name.upper(),
+        fmt=event.fmt.rstrip("\n"),
+        argnames=argnames)
diff --git a/scripts/tracetool/backend/simple.py b/scripts/tracetool/backend/simple.py
index ca48e12..e8c2cd5 100644
--- a/scripts/tracetool/backend/simple.py
+++ b/scripts/tracetool/backend/simple.py
@@ -26,76 +26,74 @@ def is_string(arg):
     else:
         return False
 
-def c(events):
+
+def generate_h_begin(events):
+    for event in events:
+        out('void _simple_%(api)s(%(args)s);',
+            api=event.api(),
+            args=event.args)
+    out('')
+
+
+def generate_h(event):
+    out('    _simple_%(api)s(%(args)s);',
+        api=event.api(),
+        args=", ".join(event.args.names()))
+
+
+def generate_c_begin(events):
     out('#include "trace.h"',
         '#include "trace/control.h"',
         '#include "trace/simple.h"',
+        '')
+
+
+def generate_c(event):
+    out('void _simple_%(api)s(%(args)s)',
+        '{',
+        '    TraceBufferRecord rec;',
+        api=event.api(),
+        args=event.args)
+    sizes = []
+    for type_, name in event.args:
+        if is_string(type_):
+            out('    size_t arg%(name)s_len = %(name)s ? MIN(strlen(%(name)s), MAX_TRACE_STRLEN) : 0;',
+                name=name)
+            strsizeinfo = "4 + arg%s_len" % name
+            sizes.append(strsizeinfo)
+        else:
+            sizes.append("8")
+    sizestr = " + ".join(sizes)
+    if len(event.args) == 0:
+        sizestr = '0'
+
+
+    out('',
+        '    if (!trace_event_get_state(%(event_id)s)) {',
+        '        return;',
+        '    }',
         '',
-        )
-
-    for num, event in enumerate(events):
-        out('void %(api)s(%(args)s)',
-            '{',
-            '    TraceBufferRecord rec;',
-            api = event.api(),
-            args = event.args,
-            )
-        sizes = []
+        '    if (trace_record_start(&rec, %(event_id)s, %(size_str)s)) {',
+        '        return; /* Trace Buffer Full, Event Dropped ! */',
+        '    }',
+        event_id='TRACE_' + event.name.upper(),
+        size_str=sizestr)
+
+    if len(event.args) > 0:
         for type_, name in event.args:
+            # string
             if is_string(type_):
-                out('    size_t arg%(name)s_len = %(name)s ? MIN(strlen(%(name)s), MAX_TRACE_STRLEN) : 0;',
-                    name = name,
-                   )
-                strsizeinfo = "4 + arg%s_len" % name
-                sizes.append(strsizeinfo)
+                out('    trace_record_write_str(&rec, %(name)s, arg%(name)s_len);',
+                    name=name)
+            # pointer var (not string)
+            elif type_.endswith('*'):
+                out('    trace_record_write_u64(&rec, (uintptr_t)(uint64_t *)%(name)s);',
+                    name=name)
+            # primitive data type
             else:
-                sizes.append("8")
-        sizestr = " + ".join(sizes)
-        if len(event.args) == 0:
-            sizestr = '0'
-
-
-        out('',
-            '    TraceEvent *eventp = trace_event_id(%(event_enum)s);',
-            '    bool _state = trace_event_get_state_dynamic(eventp);',
-            '    if (!_state) {',
-            '        return;',
-            '    }',
-            '',
-            '    if (trace_record_start(&rec, %(event_id)s, %(size_str)s)) {',
-            '        return; /* Trace Buffer Full, Event Dropped ! */',
-            '    }',
-            event_enum = 'TRACE_' + event.name.upper(),
-            event_id = num,
-            size_str = sizestr,
-            )
-
-        if len(event.args) > 0:
-            for type_, name in event.args:
-                # string
-                if is_string(type_):
-                    out('    trace_record_write_str(&rec, %(name)s, arg%(name)s_len);',
-                        name = name,
-                       )
-                # pointer var (not string)
-                elif type_.endswith('*'):
-                    out('    trace_record_write_u64(&rec, (uintptr_t)(uint64_t *)%(name)s);',
-                        name = name,
-                       )
-                # primitive data type
-                else:
-                    out('    trace_record_write_u64(&rec, (uint64_t)%(name)s);',
-                       name = name,
-                       )
-
-        out('    trace_record_finish(&rec);',
-            '}',
-            '')
-
-
-def h(events):
-    for event in events:
-        out('void %(api)s(%(args)s);',
-            api = event.api(),
-            args = event.args,
-            )
+                out('    trace_record_write_u64(&rec, (uint64_t)%(name)s);',
+                   name=name)
+
+    out('    trace_record_finish(&rec);',
+        '}',
+        '')
diff --git a/scripts/tracetool/backend/stderr.py b/scripts/tracetool/backend/stderr.py
index 6681e26..2a1e906 100644
--- a/scripts/tracetool/backend/stderr.py
+++ b/scripts/tracetool/backend/stderr.py
@@ -19,31 +19,21 @@ from tracetool import out
 PUBLIC = True
 
 
-def c(events):
-    pass
-
-def h(events):
+def generate_h_begin(events):
     out('#include <stdio.h>',
         '#include "trace/control.h"',
-        '',
-        )
-
-    for e in events:
-        argnames = ", ".join(e.args.names())
-        if len(e.args) > 0:
-            argnames = ", " + argnames
-
-        out('static inline void %(api)s(%(args)s)',
-            '{',
-            '    bool _state = trace_event_get_state(%(event_id)s);',
-            '    if (_state) {',
-            '        fprintf(stderr, "%(name)s " %(fmt)s "\\n" %(argnames)s);',
-            '    }',
-            '}',
-            api = e.api(),
-            name = e.name,
-            args = e.args,
-            event_id = "TRACE_" + e.name.upper(),
-            fmt = e.fmt.rstrip("\n"),
-            argnames = argnames,
-            )
+        '')
+
+
+def generate_h(event):
+    argnames = ", ".join(event.args.names())
+    if len(event.args) > 0:
+        argnames = ", " + argnames
+
+    out('    if (trace_event_get_state(%(event_id)s)) {',
+        '        fprintf(stderr, "%(name)s " %(fmt)s "\\n" %(argnames)s);',
+        '    }',
+        event_id="TRACE_" + event.name.upper(),
+        name=event.name,
+        fmt=event.fmt.rstrip("\n"),
+        argnames=argnames)
diff --git a/scripts/tracetool/backend/ust.py b/scripts/tracetool/backend/ust.py
index 2fca4d2..2f8f44a 100644
--- a/scripts/tracetool/backend/ust.py
+++ b/scripts/tracetool/backend/ust.py
@@ -18,66 +18,18 @@ from tracetool import out
 
 PUBLIC = True
 
-def c(events):
-    pass
 
-
-def h(events):
+def generate_h_begin(events):
     out('#include <lttng/tracepoint.h>',
         '#include "trace/generated-ust-provider.h"',
         '')
-    for e in events:
-        argnames = ", ".join(e.args.names())
-        if len(e.args) > 0:
-            argnames = ", " + argnames
-
-        out('static inline void %(api)s(%(args)s)',
-            '{',
-            '    tracepoint(qemu, %(name)s%(tp_args)s);',
-            '}',
-            '',
-            api = e.api()
-            name = e.name,
-            args = e.args,
-            tp_args = argnames,
-            )
-
-def ust_events_c(events):
-    pass
-
-def ust_events_h(events):
-    for e in events:
-        if len(e.args) > 0:
-            out('TRACEPOINT_EVENT(',
-                '   qemu,',
-                '   %(name)s,',
-                '   TP_ARGS(%(args)s),',
-                '   TP_FIELDS(',
-                name = e.name,
-                args = ", ".join(", ".join(i) for i in e.args),
-                )
 
-            for t,n in e.args:
-                if ('int' in t) or ('long' in t) or ('unsigned' in t) or ('size_t' in t):
-                    out('       ctf_integer(' + t + ', ' + n + ', ' + n + ')')
-                elif ('double' in t) or ('float' in t):
-                    out('       ctf_float(' + t + ', ' + n + ', ' + n + ')')
-                elif ('char *' in t) or ('char*' in t):
-                    out('       ctf_string(' + n + ', ' + n + ')')
-                elif ('void *' in t) or ('void*' in t):
-                    out('       ctf_integer_hex(unsigned long, ' + n + ', ' + n + ')')
 
-            out('   )',
-                ')',
-                '')
+def generate_h(event):
+    argnames = ", ".join(event.args.names())
+    if len(event.args) > 0:
+        argnames = ", " + argnames
 
-        else:
-            out('TRACEPOINT_EVENT(',
-                '   qemu,',
-                '   %(name)s,',
-                '   TP_ARGS(void),',
-                '   TP_FIELDS()',
-                ')',
-                '',
-                name = e.name,
-                )
+    out('    tracepoint(qemu, %(name)s%(tp_args)s);',
+        name=event.name,
+        tp_args=argnames)