Files
adler
aho_corasick
async_compression
async_trait
base64
bitflags
bytes
cfg_if
chrono
crc32fast
dirs
dirs_sys
dtoa
encoding_rs
eui48
fallible_iterator
flate2
fnv
foreign_types
foreign_types_shared
form_urlencoded
futures
futures_channel
futures_core
futures_executor
futures_io
futures_macro
futures_sink
futures_task
futures_util
async_await
future
io
lock
sink
stream
task
h2
hashbrown
http
http_body
httparse
httpdate
hyper
hyper_tls
idna
indexmap
iovec
ipnet
itoa
lazy_static
libc
linked_hash_map
log
matches
memchr
mime
mime_guess
miniz_oxide
mio
native_tls
net2
num_integer
num_traits
once_cell
openssl
openssl_probe
openssl_sys
openstack
osauth
osproto
percent_encoding
pin_project
pin_project_internal
pin_project_lite
pin_utils
proc_macro2
proc_macro_hack
proc_macro_nested
quote
regex
regex_syntax
reqwest
rustc_serialize
ryu
serde
serde_derive
serde_json
serde_urlencoded
serde_yaml
slab
socket2
syn
thread_local
time
tinyvec
tokio
future
io
loom
macros
net
park
runtime
stream
sync
task
time
util
tokio_macros
tokio_tls
tokio_util
tower_service
tracing
tracing_core
tracing_futures
try_lock
unicase
unicode_bidi
unicode_normalization
unicode_xid
url
waiter
want
yaml_rust
  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
use crate::task::JoinHandle;

cfg_rt_threaded! {
    /// Runs the provided blocking function on the current thread without
    /// blocking the executor.
    ///
    /// In general, issuing a blocking call or performing a lot of compute in a
    /// future without yielding is not okay, as it may prevent the executor from
    /// driving other futures forward.  This function runs the closure on the
    /// current thread by having the thread temporarily cease from being a core
    /// thread, and turns it into a blocking thread. See the [CPU-bound tasks
    /// and blocking code][blocking] section for more information.
    ///
    /// Although this function avoids starving other independently spawned
    /// tasks, any other code running concurrently in the same task will be
    /// suspended during the call to `block_in_place`. This can happen e.g. when
    /// using the [`join!`] macro. To avoid this issue, use [`spawn_blocking`]
    /// instead.
    ///
    /// Note that this function can only be used on the [threaded scheduler].
    ///
    /// Code running behind `block_in_place` cannot be cancelled. When you shut
    /// down the executor, it will wait indefinitely for all blocking operations
    /// to finish. You can use [`shutdown_timeout`] to stop waiting for them
    /// after a certain timeout. Be aware that this will still not cancel the
    /// tasks — they are simply allowed to keep running after the method
    /// returns.
    ///
    /// [blocking]: ../index.html#cpu-bound-tasks-and-blocking-code
    /// [threaded scheduler]: fn@crate::runtime::Builder::threaded_scheduler
    /// [`spawn_blocking`]: fn@crate::task::spawn_blocking
    /// [`join!`]: macro@join
    /// [`thread::spawn`]: fn@std::thread::spawn
    /// [`shutdown_timeout`]: fn@crate::runtime::Runtime::shutdown_timeout
    ///
    /// # Examples
    ///
    /// ```
    /// use tokio::task;
    ///
    /// # async fn docs() {
    /// task::block_in_place(move || {
    ///     // do some compute-heavy work or call synchronous code
    /// });
    /// # }
    /// ```
    #[cfg_attr(docsrs, doc(cfg(feature = "blocking")))]
    pub fn block_in_place<F, R>(f: F) -> R
    where
        F: FnOnce() -> R,
    {
        crate::runtime::thread_pool::block_in_place(f)
    }
}

cfg_blocking! {
    /// Runs the provided closure on a thread where blocking is acceptable.
    ///
    /// In general, issuing a blocking call or performing a lot of compute in a
    /// future without yielding is not okay, as it may prevent the executor from
    /// driving other futures forward. This function runs the provided closure
    /// on a thread dedicated to blocking operations. See the [CPU-bound tasks
    /// and blocking code][blocking] section for more information.
    ///
    /// Tokio will spawn more blocking threads when they are requested through
    /// this function until the upper limit configured on the [`Builder`] is
    /// reached.  This limit is very large by default, because `spawn_blocking` is
    /// often used for various kinds of IO operations that cannot be performed
    /// asynchronously. When you run CPU-bound code using `spawn_blocking`, you
    /// should keep this large upper limit in mind; to run your CPU-bound
    /// computations on only a few threads, you should use a separate thread
    /// pool such as [rayon] rather than configuring the number of blocking
    /// threads.
    ///
    /// This function is intended for non-async operations that eventually
    /// finish on their own. If you want to spawn an ordinary thread, you should
    /// use [`thread::spawn`] instead.
    ///
    /// Closures spawned using `spawn_blocking` cannot be cancelled. When you
    /// shut down the executor, it will wait indefinitely for all blocking
    /// operations to finish. You can use [`shutdown_timeout`] to stop waiting
    /// for them after a certain timeout. Be aware that this will still not
    /// cancel the tasks — they are simply allowed to keep running after the
    /// method returns.
    ///
    /// Note that if you are using the [basic scheduler], this function will
    /// still spawn additional threads for blocking operations. The basic
    /// scheduler's single thread is only used for asynchronous code.
    ///
    /// [`Builder`]: struct@crate::runtime::Builder
    /// [blocking]: ../index.html#cpu-bound-tasks-and-blocking-code
    /// [rayon]: https://docs.rs/rayon
    /// [basic scheduler]: fn@crate::runtime::Builder::basic_scheduler
    /// [`thread::spawn`]: fn@std::thread::spawn
    /// [`shutdown_timeout`]: fn@crate::runtime::Runtime::shutdown_timeout
    ///
    /// # Examples
    ///
    /// ```
    /// use tokio::task;
    ///
    /// # async fn docs() -> Result<(), Box<dyn std::error::Error>>{
    /// let res = task::spawn_blocking(move || {
    ///     // do some compute-heavy work or call synchronous code
    ///     "done computing"
    /// }).await?;
    ///
    /// assert_eq!(res, "done computing");
    /// # Ok(())
    /// # }
    /// ```
    pub fn spawn_blocking<F, R>(f: F) -> JoinHandle<R>
    where
        F: FnOnce() -> R + Send + 'static,
        R: Send + 'static,
    {
        #[cfg(feature = "tracing")]
        let f = {
            let span = tracing::trace_span!(
                target: "tokio::task",
                "task",
                kind = %"blocking",
                function = %std::any::type_name::<F>(),
            );
            move || {
                let _g = span.enter();
                f()
            }
        };
        crate::runtime::spawn_blocking(f)
    }
}