1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
#![doc(html_root_url = "https://docs.rs/tokio-macros/1.0.0")]
#![allow(clippy::needless_doctest_main)]
#![warn(
    missing_debug_implementations,
    missing_docs,
    rust_2018_idioms,
    unreachable_pub
)]
#![cfg_attr(docsrs, deny(broken_intra_doc_links))]
#![doc(test(
    no_crate_inject,
    attr(deny(warnings, rust_2018_idioms), allow(dead_code, unused_variables))
))]

//! Macros for use with Tokio

// This `extern` is required for older `rustc` versions but newer `rustc`
// versions warn about the unused `extern crate`.
#[allow(unused_extern_crates)]
extern crate proc_macro;

mod entry;
mod select;

use proc_macro::TokenStream;

/// Marks async function to be executed by the selected runtime. This macro
/// helps set up a `Runtime` without requiring the user to use
/// [Runtime](../tokio/runtime/struct.Runtime.html) or
/// [Builder](../tokio/runtime/struct.Builder.html) directly.
///
/// Note: This macro is designed to be simplistic and targets applications that
/// do not require a complex setup. If the provided functionality is not
/// sufficient, you may be interested in using
/// [Builder](../tokio/runtime/struct.Builder.html), which provides a more
/// powerful interface.
///
/// Note: This macro can be used on any function and not just the `main`
/// function. Using it on a non-main function makes the function behave as if it
/// was synchronous by starting a new runtime each time it is called. If the
/// function is called often, it is preferable to create the runtime using the
/// runtime builder so the runtime can be reused across calls.
///
/// # Multi-threaded runtime
///
/// To use the multi-threaded runtime, the macro can be configured using
///
/// ```
/// #[tokio::main(flavor = "multi_thread", worker_threads = 10)]
/// # async fn main() {}
/// ```
///
/// The `worker_threads` option configures the number of worker threads, and
/// defaults to the number of cpus on the system. This is the default flavor.
///
/// Note: The multi-threaded runtime requires the `rt-multi-thread` feature
/// flag.
///
/// # Current thread runtime
///
/// To use the single-threaded runtime known as the `current_thread` runtime,
/// the macro can be configured using
///
/// ```
/// #[tokio::main(flavor = "current_thread")]
/// # async fn main() {}
/// ```
///
/// ## Function arguments:
///
/// Arguments are allowed for any functions aside from `main` which is special
///
/// ## Usage
///
/// ### Using the multi-thread runtime
///
/// ```rust
/// #[tokio::main]
/// async fn main() {
///     println!("Hello world");
/// }
/// ```
///
/// Equivalent code not using `#[tokio::main]`
///
/// ```rust
/// fn main() {
///     tokio::runtime::Builder::new_multi_thread()
///         .enable_all()
///         .build()
///         .unwrap()
///         .block_on(async {
///             println!("Hello world");
///         })
/// }
/// ```
///
/// ### Using current thread runtime
///
/// The basic scheduler is single-threaded.
///
/// ```rust
/// #[tokio::main(flavor = "current_thread")]
/// async fn main() {
///     println!("Hello world");
/// }
/// ```
///
/// Equivalent code not using `#[tokio::main]`
///
/// ```rust
/// fn main() {
///     tokio::runtime::Builder::new_current_thread()
///         .enable_all()
///         .build()
///         .unwrap()
///         .block_on(async {
///             println!("Hello world");
///         })
/// }
/// ```
///
/// ### Set number of worker threads
///
/// ```rust
/// #[tokio::main(worker_threads = 2)]
/// async fn main() {
///     println!("Hello world");
/// }
/// ```
///
/// Equivalent code not using `#[tokio::main]`
///
/// ```rust
/// fn main() {
///     tokio::runtime::Builder::new_multi_thread()
///         .worker_threads(2)
///         .enable_all()
///         .build()
///         .unwrap()
///         .block_on(async {
///             println!("Hello world");
///         })
/// }
/// ```
///
/// ### NOTE:
///
/// If you rename the Tokio crate in your dependencies this macro will not work.
/// If you must rename the current version of Tokio because you're also using an
/// older version of Tokio, you _must_ make the current version of Tokio
/// available as `tokio` in the module where this macro is expanded.
#[proc_macro_attribute]
#[cfg(not(test))] // Work around for rust-lang/rust#62127
pub fn main(args: TokenStream, item: TokenStream) -> TokenStream {
    entry::main(args, item, true)
}

/// Marks async function to be executed by selected runtime. This macro helps set up a `Runtime`
/// without requiring the user to use [Runtime](../tokio/runtime/struct.Runtime.html) or
/// [Builder](../tokio/runtime/struct.builder.html) directly.
///
/// ## Function arguments:
///
/// Arguments are allowed for any functions aside from `main` which is special
///
/// ## Usage
///
/// ### Using default
///
/// ```rust
/// #[tokio::main(flavor = "current_thread")]
/// async fn main() {
///     println!("Hello world");
/// }
/// ```
///
/// Equivalent code not using `#[tokio::main]`
///
/// ```rust
/// fn main() {
///     tokio::runtime::Builder::new_current_thread()
///         .enable_all()
///         .build()
///         .unwrap()
///         .block_on(async {
///             println!("Hello world");
///         })
/// }
/// ```
///
/// ### NOTE:
///
/// If you rename the Tokio crate in your dependencies this macro will not work.
/// If you must rename the current version of Tokio because you're also using an
/// older version of Tokio, you _must_ make the current version of Tokio
/// available as `tokio` in the module where this macro is expanded.
#[proc_macro_attribute]
#[cfg(not(test))] // Work around for rust-lang/rust#62127
pub fn main_rt(args: TokenStream, item: TokenStream) -> TokenStream {
    entry::main(args, item, false)
}

/// Marks async function to be executed by runtime, suitable to test environment
///
/// ## Usage
///
/// ### Multi-thread runtime
///
/// ```no_run
/// #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
/// async fn my_test() {
///     assert!(true);
/// }
/// ```
///
/// ### Using default
///
/// The default test runtime is single-threaded.
///
/// ```no_run
/// #[tokio::test]
/// async fn my_test() {
///     assert!(true);
/// }
/// ```
///
/// ### NOTE:
///
/// If you rename the Tokio crate in your dependencies this macro will not work.
/// If you must rename the current version of Tokio because you're also using an
/// older version of Tokio, you _must_ make the current version of Tokio
/// available as `tokio` in the module where this macro is expanded.
#[proc_macro_attribute]
pub fn test(args: TokenStream, item: TokenStream) -> TokenStream {
    entry::test(args, item, true)
}

/// Marks async function to be executed by runtime, suitable to test environment
///
/// ## Usage
///
/// ```no_run
/// #[tokio::test]
/// async fn my_test() {
///     assert!(true);
/// }
/// ```
///
/// ### NOTE:
///
/// If you rename the Tokio crate in your dependencies this macro will not work.
/// If you must rename the current version of Tokio because you're also using an
/// older version of Tokio, you _must_ make the current version of Tokio
/// available as `tokio` in the module where this macro is expanded.
#[proc_macro_attribute]
pub fn test_rt(args: TokenStream, item: TokenStream) -> TokenStream {
    entry::test(args, item, false)
}

/// Always fails with the error message below.
/// ```text
/// The #[tokio::main] macro requires rt or rt-multi-thread.
/// ```
#[proc_macro_attribute]
pub fn main_fail(_args: TokenStream, _item: TokenStream) -> TokenStream {
    syn::Error::new(
        proc_macro2::Span::call_site(),
        "The #[tokio::main] macro requires rt or rt-multi-thread.",
    )
    .to_compile_error()
    .into()
}

/// Always fails with the error message below.
/// ```text
/// The #[tokio::test] macro requires rt or rt-multi-thread.
/// ```
#[proc_macro_attribute]
pub fn test_fail(_args: TokenStream, _item: TokenStream) -> TokenStream {
    syn::Error::new(
        proc_macro2::Span::call_site(),
        "The #[tokio::test] macro requires rt or rt-multi-thread.",
    )
    .to_compile_error()
    .into()
}

/// Implementation detail of the `select!` macro. This macro is **not** intended
/// to be used as part of the public API and is permitted to change.
#[proc_macro]
#[doc(hidden)]
pub fn select_priv_declare_output_enum(input: TokenStream) -> TokenStream {
    select::declare_output_enum(input)
}