1 /*
2 * Copyright (C) 2020 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #ifndef SRC_TRACE_PROCESSOR_SQLITE_REGISTER_FUNCTION_H_
18 #define SRC_TRACE_PROCESSOR_SQLITE_REGISTER_FUNCTION_H_
19
20 #include <sqlite3.h>
21 #include <memory>
22
23 #include "src/trace_processor/sqlite/sqlite_utils.h"
24
25 namespace perfetto {
26 namespace trace_processor {
27
28 // Prototype for a C++ function which can be registered with SQLite.
29 //
30 // Usage
31 //
32 // Define a subclass of this struct as follows:
33 // struct YourFunction : public SqlFunction {
34 // // Optional if you want a custom context object (i.e. an object
35 // // passed in at registration time which will be passed to Run on
36 // // every invocation)
37 // struct YourContext { /* define context fields here */ };
38 //
39 // static base::Status Run(/* see parameters below */) {
40 // /* function body here */
41 // }
42 //
43 // static base::Status Cleanup(/* see parameters below */) {
44 // /* function body here */
45 // }
46 // }
47 //
48 // Then, register this function with SQLite using RegisterFunction (see below);
49 // you'll likely want to do this in TraceProcessorImpl:
50 // RegisterFunction<YourFunction>(/* see arguments below */)
51 struct SqlFunction {
52 // The type of the context object which will be passed to the function.
53 // Can be redefined in any sub-classes to override the context.
54 using Context = void;
55
56 // Struct which holds destructors for strings/bytes returned from the
57 // function. Passed as an argument to |Run| to allow implementations to
58 // override the destructors.
59 struct Destructors {
60 sqlite3_destructor_type string_destructor = sqlite_utils::kSqliteTransient;
61 sqlite3_destructor_type bytes_destructor = sqlite_utils::kSqliteTransient;
62 };
63
64 // The function which will be exectued with the arguments from SQL.
65 //
66 // Implementations MUST define this function themselves; this function is
67 // declared but *not* defined so linker errors will be thrown if not defined.
68 //
69 // |ctx|: the context object passed at registration time.
70 // |argc|: number of arguments.
71 // |argv|: arguments to the function.
72 // |out|: the return value of the function.
73 // |destructors|: destructors for string/bytes return values.
74 static base::Status Run(Context* ctx,
75 size_t argc,
76 sqlite3_value** argv,
77 SqlValue& out,
78 Destructors& destructors);
79
80 // Executed after the result from |Run| is reported to SQLite.
81 // Allows any pending state to be cleaned up post-copy of results by SQLite.
82 //
83 // Implementations do not need to define this function; a default no-op
84 // implementation will be used in this case.
85 static base::Status Cleanup(Context*);
86 };
87
88 // Registers a C++ function to be runnable from SQL.
89 // The format of the function is given by the |SqlFunction|; see the
90 // documentaion above.
91 //
92 // |db|: sqlite3 database object
93 // |name|: name of the function in SQL
94 // |argc|: number of arguments for this function, -1 if variable
95 // |ctx|: context object for the function (see SqlFunction::Run above);
96 // this object *must* outlive the function so should likely be
97 // either static or scoped to the lifetime of TraceProcessor.
98 // |determistic|: whether this function has deterministic output given the
99 // same set of arguments.
100 template <typename Function>
101 base::Status RegisterSqlFunction(sqlite3* db,
102 const char* name,
103 int argc,
104 typename Function::Context* ctx,
105 bool deterministic = true);
106
107 // Same as above except allows a unique_ptr to be passed for the context; this
108 // allows for SQLite to manage the lifetime of this pointer instead of the
109 // essentially static requirement of the context pointer above.
110 template <typename Function>
111 base::Status RegisterSqlFunction(
112 sqlite3* db,
113 const char* name,
114 int argc,
115 std::unique_ptr<typename Function::Context> ctx,
116 bool deterministic = true);
117
118 } // namespace trace_processor
119 } // namespace perfetto
120
121 // The rest of this file is just implementation details which we need
122 // in the header file because it is templated code. We separate it out
123 // like this to keep the API people actually care about easy to read.
124
125 namespace perfetto {
126 namespace trace_processor {
127
128 namespace sqlite_internal {
129 template <typename Function>
WrapSqlFunction(sqlite3_context * ctx,int argc,sqlite3_value ** argv)130 void WrapSqlFunction(sqlite3_context* ctx, int argc, sqlite3_value** argv) {
131 using Context = typename Function::Context;
132 auto* ud = static_cast<Context*>(sqlite3_user_data(ctx));
133
134 SqlValue value{};
135 SqlFunction::Destructors destructors{};
136 base::Status status =
137 Function::Run(ud, static_cast<size_t>(argc), argv, value, destructors);
138
139 if (!status.ok()) {
140 sqlite3_result_error(ctx, status.c_message(), -1);
141 return;
142 }
143 sqlite_utils::ReportSqlValue(ctx, value, destructors.string_destructor,
144 destructors.bytes_destructor);
145
146 status = Function::Cleanup(ud);
147 if (!status.ok()) {
148 sqlite3_result_error(ctx, status.c_message(), -1);
149 return;
150 }
151 }
152 } // namespace sqlite_internal
153
154 template <typename Function>
RegisterSqlFunction(sqlite3 * db,const char * name,int argc,typename Function::Context * ctx,bool deterministic)155 base::Status RegisterSqlFunction(sqlite3* db,
156 const char* name,
157 int argc,
158 typename Function::Context* ctx,
159 bool deterministic) {
160 int flags = SQLITE_UTF8 | (deterministic ? SQLITE_DETERMINISTIC : 0);
161 int ret = sqlite3_create_function_v2(
162 db, name, static_cast<int>(argc), flags, ctx,
163 sqlite_internal::WrapSqlFunction<Function>, nullptr, nullptr, nullptr);
164 if (ret != SQLITE_OK) {
165 return base::ErrStatus("Unable to register function with name %s", name);
166 }
167 return base::OkStatus();
168 }
169
170 template <typename Function>
RegisterSqlFunction(sqlite3 * db,const char * name,int argc,std::unique_ptr<typename Function::Context> user_data,bool deterministic)171 base::Status RegisterSqlFunction(
172 sqlite3* db,
173 const char* name,
174 int argc,
175 std::unique_ptr<typename Function::Context> user_data,
176 bool deterministic) {
177 int flags = SQLITE_UTF8 | (deterministic ? SQLITE_DETERMINISTIC : 0);
178 int ret = sqlite3_create_function_v2(
179 db, name, static_cast<int>(argc), flags, user_data.release(),
180 sqlite_internal::WrapSqlFunction<Function>, nullptr, nullptr,
181 [](void* ptr) { delete static_cast<typename Function::Context*>(ptr); });
182 if (ret != SQLITE_OK) {
183 return base::ErrStatus("Unable to register function with name %s", name);
184 }
185 return base::OkStatus();
186 }
187
188 } // namespace trace_processor
189 } // namespace perfetto
190
191 #endif // SRC_TRACE_PROCESSOR_SQLITE_REGISTER_FUNCTION_H_
192