[Qemu-devel] [RFC PATCH V2 3/5] qapi script: add event support by qapi-event.py

[Wenchao Xia]

qapi-event.py will parse the schema and generate qapi-event.c, then
the API in qapi-event.c can be used to handle event in qemu code.
All API have prefix "qapi_event", all types have prefix "QAPIEvent".
Examples can be found in following patches.

The script mainly include three parts: generate API for each event
define, generate an enum type for all defined event, generate behavior
control functions.

Since in some case the real emit behavior may change, for example,
qemu-img would not send a event, a callback layer is added to
control the behavior. As a result, the stubs at compile time
can be saved, the binding of block layer code and monitor code
will become looser.

Signed-off-by: Wenchao Xia <address@hidden>
---
 Makefile              |    9 +-
 Makefile.objs         |    2 +-
 scripts/qapi-event.py |  432 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 439 insertions(+), 4 deletions(-)
 create mode 100644 scripts/qapi-event.py

diff --git a/Makefile b/Makefile
index bdff4e4..fa59765 100644
--- a/Makefile
+++ b/Makefile
@@ -45,8 +45,8 @@ endif
 endif
 
 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 += qmp-commands.h qapi-types.h qapi-visit.h qapi-event.h
+GENERATED_SOURCES += qmp-marshal.c qapi-types.c qapi-visit.c qapi-event.c
 
 GENERATED_HEADERS += trace/generated-events.h
 GENERATED_SOURCES += trace/generated-events.c
@@ -185,7 +185,7 @@ Makefile: $(version-obj-y) $(version-lobj-y)
 # Build libraries
 
 libqemustub.a: $(stub-obj-y)
-libqemuutil.a: $(util-obj-y) qapi-types.o qapi-visit.o
+libqemuutil.a: $(util-obj-y) qapi-types.o qapi-visit.o qapi-event.o
 
 ######################################################################
 
@@ -226,6 +226,9 @@ $(SRC_PATH)/qapi-schema.json 
$(SRC_PATH)/scripts/qapi-types.py $(qapi-py)
 qapi-visit.c qapi-visit.h :\
 $(SRC_PATH)/qapi-schema.json $(SRC_PATH)/scripts/qapi-visit.py $(qapi-py)
        $(call quiet-command,$(PYTHON) $(SRC_PATH)/scripts/qapi-visit.py 
$(gen-out-type) -o "." -b < $<, "  GEN   $@")
+qapi-event.c qapi-event.h :\
+$(SRC_PATH)/qapi-schema.json $(SRC_PATH)/scripts/qapi-event.py $(qapi-py)
+       $(call quiet-command,$(PYTHON) $(SRC_PATH)/scripts/qapi-event.py 
$(gen-out-type) -o "." -b < $<, "  GEN   $@")
 qmp-commands.h qmp-marshal.c :\
 $(SRC_PATH)/qapi-schema.json $(SRC_PATH)/scripts/qapi-commands.py $(qapi-py)
        $(call quiet-command,$(PYTHON) $(SRC_PATH)/scripts/qapi-commands.py 
$(gen-out-type) -m -o "." < $<, "  GEN   $@")
diff --git a/Makefile.objs b/Makefile.objs
index 2b6c1fe..33f5950 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -12,7 +12,7 @@ block-obj-y += main-loop.o iohandler.o qemu-timer.o
 block-obj-$(CONFIG_POSIX) += aio-posix.o
 block-obj-$(CONFIG_WIN32) += aio-win32.o
 block-obj-y += block/
-block-obj-y += qapi-types.o qapi-visit.o
+block-obj-y += qapi-types.o qapi-visit.o qapi-event.o
 block-obj-y += qemu-io-cmds.o
 
 block-obj-y += qemu-coroutine.o qemu-coroutine-lock.o qemu-coroutine-io.o
diff --git a/scripts/qapi-event.py b/scripts/qapi-event.py
new file mode 100644
index 0000000..7526366
--- /dev/null
+++ b/scripts/qapi-event.py
@@ -0,0 +1,432 @@
+#
+# QAPI event generator
+#
+# Copyright IBM, Corp. 2014
+#
+# Authors:
+#  Wenchao Xia <address@hidden>
+#
+# This work is licensed under the terms of the GNU GPLv2+ or later.
+# See the COPYING.LIB file in the top-level directory.
+
+from ordereddict import OrderedDict
+from qapi import *
+import sys
+import os
+import getopt
+import errno
+
+def _generate_event_api_name(event_name, params):
+    api_name = "void qapi_event_send_%s(" % c_fun(event_name).lower();
+    l = len(api_name)
+
+    if params:
+        for argname, argentry, optional, structured in parse_args(params):
+            if structured:
+                sys.stderr.write("Nested structure define in event is not "
+                                 "supported now, event '%s', argname '%s'\n" %
+                                 (event_name, argname))
+                sys.exit(1)
+                continue
+
+            if optional:
+                api_name += "bool has_%s,\n" % c_var(argname)
+                api_name += "".ljust(l)
+
+            if argentry == "str":
+                api_name += "const "
+            api_name += "%s %s,\n" % (c_type(argentry), c_var(argname))
+            api_name += "".ljust(l)
+
+    api_name += "Error **errp)"
+    return api_name;
+
+
+# Following are the core functions that transate user input into a qdict going
+# to be emitted in the wire.
+
+def generate_event_declaration(api_name):
+    return mcgen('''
+
+%(api_name)s;
+''',
+                 api_name = api_name)
+
+def generate_event_implement(api_name, event_name, params):
+    # step 1: declare and variables
+    ret = mcgen("""
+
+%(api_name)s
+{
+    QDict *qmp;
+    Error *local_err = NULL;
+    QAPIEventFuncEmit emit;
+""",
+                api_name = api_name)
+
+    if params:
+        ret += mcgen("""
+    QmpOutputVisitor *qov;
+    Visitor *v;
+    QObject *obj;
+
+""")
+
+    # step 2: check emit function, create a dict
+    ret += mcgen("""
+    emit = qapi_event_get_func_emit();
+    if (!emit) {
+        return;
+    }
+
+    qmp = qmp_event_build_dict("%(event_name)s");
+
+""",
+                 event_name = event_name)
+
+    # step 3: visit the params if params != None
+    if params:
+        ret += mcgen("""
+    qov = qmp_output_visitor_new();
+    g_assert(qov);
+
+    v = qmp_output_get_visitor(qov);
+    g_assert(v);
+
+    /* Fake visit, as if all member are under a structure */
+    visit_start_struct(v, NULL, "", "%(event_name)s", 0, &local_err);
+    if (error_is_set(&local_err)) {
+        goto clean;
+    }
+
+""",
+                event_name = event_name)
+
+        for argname, argentry, optional, structured in parse_args(params):
+            if structured:
+                sys.stderr.write("Nested structure define in event is not "
+                                 "supported now, event '%s', argname '%s'\n" %
+                                 (event_name, argname))
+                sys.exit(1)
+
+            if optional:
+                ret += mcgen("""
+    if (has_%(var)s) {
+""",
+                             var = c_var(argname))
+                push_indent()
+
+            if argentry == "str":
+                var_type = "(char **)"
+            else:
+                var_type = ""
+
+            ret += mcgen("""
+    visit_type_%(type)s(v, %(var_type)s&%(var)s, "%(name)s", &local_err);
+    if (error_is_set(&local_err)) {
+        goto clean;
+    }
+""",
+                         var_type = var_type,
+                         var = c_var(argname),
+                         type = type_name(argentry),
+                         name = argname)
+
+            if optional:
+                pop_indent()
+                ret += mcgen("""
+    }
+""")
+
+        ret += mcgen("""
+
+    visit_end_struct(v, &local_err);
+    if (error_is_set(&local_err)) {
+        goto clean;
+    }
+
+    obj = qmp_output_get_qobject(qov);
+    g_assert(obj != NULL);
+
+    qdict_put_obj(qmp, "data", obj);
+""")
+
+    # step 4: call qmp event api
+    ret += mcgen("""
+    emit(%(event_enum_value)s, qmp, &local_err);
+
+""",
+                 event_enum_value = event_enum_value)
+
+    # step 5: clean up
+    if params:
+        ret += mcgen("""
+ clean:
+    qmp_output_visitor_cleanup(qov);
+""")
+    ret += mcgen("""
+    error_propagate(errp, local_err);
+    QDECREF(qmp);
+}
+""")
+
+    return ret
+
+
+# Following are the functions that generate an enum type for all defined
+# events, similar with qapi-types.py. Here we already have enum name and
+# values which is generated before and recorded in event_enum_*. It also
+# walk around the issue that "import qapi-types" can't work.
+
+def generate_event_enum_decl(event_enum_name, event_enum_values):
+    lookup_decl = mcgen('''
+
+extern const char *%(event_enum_name)s_lookup[];
+''',
+                        event_enum_name = event_enum_name)
+
+    enum_decl = mcgen('''
+typedef enum %(event_enum_name)s
+{
+''',
+                      event_enum_name = event_enum_name)
+
+    # append automatically generated _MAX value
+    enum_max_value = generate_enum_full_value_string(event_enum_name, "MAX")
+    enum_values = event_enum_values + [ enum_max_value ]
+
+    i = 0
+    for value in enum_values:
+        enum_decl += mcgen('''
+    %(value)s = %(i)d,
+''',
+                     value = value,
+                     i = i)
+        i += 1
+
+    enum_decl += mcgen('''
+} %(event_enum_name)s;
+''',
+                       event_enum_name = event_enum_name)
+
+    return lookup_decl + enum_decl
+
+def generate_event_enum_lookup(event_enum_name, event_enum_strings):
+    ret = mcgen('''
+
+const char *%(event_enum_name)s_lookup[] = {
+''',
+                event_enum_name = event_enum_name)
+
+    i = 0
+    for string in event_enum_strings:
+        ret += mcgen('''
+    "%(string)s",
+''',
+                     string = string)
+
+    ret += mcgen('''
+    NULL,
+};
+''')
+    return ret
+
+
+# Following are the functions that generate event behavior control functions.
+# Those functions are put here in the qapi-event.c, since it need to include
+# qapi-event.h for the event enum type declaration, put them in other file
+# requiring other file include qapi-event.h, causing a cross including. For
+# example: if we have qmp-event.c and qmp-event.h, then qmp-event.c
+# ->qmp-event.h->qapi-event.h, qapi-event.c->qmp-event.h. Another problem
+# follow: test-qapi-event.c will meet event enum double declaration since it
+# include both test-qapi-event.h and qmp-event.h. One solution is putting event
+# enum declaration in a separate header file, but then qmp-event.h need to
+# include test-qapi-event.h or qapi-event.h on compile time condition. So the
+# easist way is, just generate them here.
+
+def generate_event_behavior_control_decl(event_enum_name):
+    ret = mcgen('''
+
+typedef void (*QAPIEventFuncEmit)(%(event_enum_name)s ev,
+                                  QDict *dict,
+                                  Error **errp);
+
+void qapi_event_set_func_emit(QAPIEventFuncEmit emit);
+
+QAPIEventFuncEmit qapi_event_get_func_emit(void);
+''',
+                event_enum_name = event_enum_name)
+    return ret;
+
+def generate_event_behavior_control_implement():
+    ret = mcgen('''
+
+typedef struct QAPIEventFunctions {
+    QAPIEventFuncEmit emit;
+} QAPIEventFunctions;
+
+QAPIEventFunctions qapi_event_functions;
+
+void qapi_event_set_func_emit(QAPIEventFuncEmit emit)
+{
+    qapi_event_functions.emit = emit;
+}
+
+QAPIEventFuncEmit qapi_event_get_func_emit(void)
+{
+    return qapi_event_functions.emit;
+}
+''')
+    return ret
+
+
+# Start the real job
+
+try:
+    opts, args = getopt.gnu_getopt(sys.argv[1:], "chbp:o:",
+                                   ["source", "header", "builtins", "prefix=",
+                                    "output-dir="])
+except getopt.GetoptError, err:
+    print str(err)
+    sys.exit(1)
+
+output_dir = ""
+prefix = ""
+c_file = 'qapi-event.c'
+h_file = 'qapi-event.h'
+
+do_c = False
+do_h = False
+do_builtins = False
+
+for o, a in opts:
+    if o in ("-p", "--prefix"):
+        prefix = a
+    elif o in ("-o", "--output-dir"):
+        output_dir = a + "/"
+    elif o in ("-c", "--source"):
+        do_c = True
+    elif o in ("-h", "--header"):
+        do_h = True
+    elif o in ("-b", "--builtins"):
+        do_builtins = True
+
+if not do_c and not do_h:
+    do_c = True
+    do_h = True
+
+c_file = output_dir + prefix + c_file
+h_file = output_dir + prefix + h_file
+
+try:
+    os.makedirs(output_dir)
+except os.error, e:
+    if e.errno != errno.EEXIST:
+        raise
+
+def maybe_open(really, name, opt):
+    if really:
+        return open(name, opt)
+    else:
+        import StringIO
+        return StringIO.StringIO()
+
+fdef = maybe_open(do_c, c_file, 'w')
+fdecl = maybe_open(do_h, h_file, 'w')
+
+fdef.write(mcgen('''
+/* THIS FILE IS AUTOMATICALLY GENERATED, DO NOT MODIFY */
+
+/*
+ * schema-defined QAPI event functions
+ *
+ * Copyright IBM, Corp. 2014
+ *
+ * Authors:
+ *  Wenchao Xia   <address@hidden>
+ *
+ * This work is licensed under the terms of the GNU GPLv2+ or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+
+#include "qemu-common.h"
+#include "%(header)s"
+#include "%(prefix)sqapi-visit.h"
+#include "qapi/qmp-output-visitor.h"
+#include "qapi/qmp-event.h"
+
+''',
+                 prefix=prefix, header=basename(h_file)))
+
+fdecl.write(mcgen('''
+/* THIS FILE IS AUTOMATICALLY GENERATED, DO NOT MODIFY */
+
+/*
+ * schema-defined QAPI event function
+ *
+ * Copyright IBM, Corp. 2014
+ *
+ * Authors:
+ *  Wenchao Xia  <address@hidden>
+ *
+ * This work is licensed under the terms of the GNU GPLv2+ or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+
+#ifndef %(guard)s
+#define %(guard)s
+
+#include "qapi/error.h"
+#include "qapi/qmp/qdict.h"
+#include "%(prefix)sqapi-types.h"
+
+''',
+                  prefix=prefix, guard=guardname(h_file)))
+
+exprs = parse_schema(sys.stdin)
+
+event_enum_name = "QAPIEvent"
+event_enum_values = []
+event_enum_strings = []
+
+for expr in exprs:
+    if expr.has_key('event'):
+        event_name = expr['event']
+        params = expr.get('data')
+        if params and len(params) == 0:
+            params = None
+
+        api_name = _generate_event_api_name(event_name, params)
+        ret = generate_event_declaration(api_name)
+        fdecl.write(ret)
+
+        # We need an enum value per event
+        event_enum_value = generate_enum_full_value_string(event_enum_name,
+                                                           event_name)
+        ret = generate_event_implement(api_name, event_name, params)
+        fdef.write(ret)
+
+        # Record it, and generate enum later
+        event_enum_values.append(event_enum_value)
+        event_enum_strings.append(event_name)
+
+ret = generate_event_enum_decl(event_enum_name, event_enum_values)
+fdecl.write(ret)
+ret = generate_event_enum_lookup(event_enum_name, event_enum_strings)
+fdef.write(ret)
+ret = generate_event_behavior_control_decl(event_enum_name)
+fdecl.write(ret)
+ret = generate_event_behavior_control_implement()
+fdef.write(ret)
+
+fdecl.write('''
+#endif
+''')
+
+fdecl.flush()
+fdecl.close()
+
+fdef.flush()
+fdef.close()
-- 
1.7.1