Add Notifications::next_block_for method

The setup is a little hairy, but seems correct.

cc #19

Author: sfackler

Cargo.toml

@@ -20,21 +20,18 @@ name = "test"
 path = "tests/test.rs"
 
 [features]
-default = ["uuid", "time"]
+default = ["uuid"]
 
 [dependencies]
 phf = "0.1"
 phf_mac = "0.1"
 openssl = "0.2.1"
+time = "0.1"
 
 [dependencies.uuid]
 optional = true
 version = "0.1"
 
-[dependencies.time]
-optional = true
-version = "0.1"
-
 [dev-dependencies]
 url = "0.2"
 

README.md

@@ -204,10 +204,7 @@ types. The driver currently supports the following conversions:
             <td>JSON</td>
         </tr>
         <tr>
-            <td>
-                <a href="https://github.com/rust-lang/time">time::Timespec</a>
-                (<a href="#optional-features">optional</a>)
-            </td>
+            <td>time::Timespec</td>
             <td>TIMESTAMP, TIMESTAMP WITH TIME ZONE</td>
         </tr>
         <tr>
@@ -226,10 +223,7 @@ types. The driver currently supports the following conversions:
             <td>INT8RANGE</td>
         </tr>
         <tr>
-            <td>
-                <a href="https://github.com/rust-lang/time">types::range::Range&lt;Timespec&gt;</a>
-                (<a href="#optional-features">optional</a>)
-            </td>
+            <td>types::range::Range&lt;Timespec&gt;</td>
             <td>TSRANGE, TSTZRANGE</td>
         </tr>
         <tr>
@@ -265,10 +259,7 @@ types. The driver currently supports the following conversions:
             <td>INT8[], INT8[][], ...</td>
         </tr>
         <tr>
-            <td>
-                <a href="https://github.com/rust-lang/time">types::array::ArrayBase&lt;Option&lt;Timespec&gt;&gt;</a>
-                (<a href="#optional-features">optional</a>)
-            </td>
+            <td>types::array::ArrayBase&lt;Option&lt;Timespec&gt;&gt;</td>
             <td>TIMESTAMP[], TIMESTAMPTZ[], TIMESTAMP[][], ...</td>
         </tr>
         <tr>
@@ -308,10 +299,6 @@ traits.
 [UUID](http://www.postgresql.org/docs/9.4/static/datatype-uuid.html) support is
 provided optionally by the `uuid` feature. It is enabled by default.
 
-### Time types
-[Time](http://www.postgresql.org/docs/9.3/static/datatype-datetime.html)
-support is provided optionally by the `time` feature. It is enabled by default.
-
 To disable support for optional features, add `default-features = false` to
 your Cargo manifest:
 

src/io.rs

@@ -1,8 +1,9 @@
 use openssl::ssl::{SslStream, MaybeSslStream};
+use std::io::BufferedStream;
 use std::io::net::ip::Port;
 use std::io::net::tcp::TcpStream;
 use std::io::net::pipe::UnixStream;
-use std::io::IoResult;
+use std::io::{IoResult, Stream};
 
 use {ConnectParams, SslMode, ConnectTarget, ConnectError};
 use message;
@@ -11,6 +12,23 @@ use message::FrontendMessage::SslRequest;
 
 const DEFAULT_PORT: Port = 5432;
 
+#[doc(hidden)]
+pub trait Timeout {
+    fn set_read_timeout(&mut self, timeout_ms: Option<u64>);
+}
+
+impl<S: Stream+Timeout> Timeout for MaybeSslStream<S> {
+    fn set_read_timeout(&mut self, timeout_ms: Option<u64>) {
+        self.get_mut().set_read_timeout(timeout_ms);
+    }
+}
+
+impl<S: Stream+Timeout> Timeout for BufferedStream<S> {
+    fn set_read_timeout(&mut self, timeout_ms: Option<u64>) {
+        self.get_mut().set_read_timeout(timeout_ms);
+    }
+}
+
 pub enum InternalStream {
     Tcp(TcpStream),
     Unix(UnixStream),
@@ -41,9 +59,8 @@ impl Writer for InternalStream {
     }
 }
 
-impl InternalStream {
-    #[allow(dead_code)]
-    pub fn set_read_timeout(&mut self, timeout_ms: Option<u64>) {
+impl Timeout for InternalStream {
+    fn set_read_timeout(&mut self, timeout_ms: Option<u64>) {
         match *self {
             InternalStream::Tcp(ref mut s) => s.set_read_timeout(timeout_ms),
             InternalStream::Unix(ref mut s) => s.set_read_timeout(timeout_ms),

src/lib.rs

@@ -65,21 +65,23 @@ extern crate phf;
 extern crate phf_mac;
 #[phase(plugin, link)]
 extern crate log;
+extern crate time;
 
 use url::Url;
 use openssl::crypto::hash::{HashType, Hasher};
 use openssl::ssl::{SslContext, MaybeSslStream};
 use serialize::hex::ToHex;
 use std::cell::{Cell, RefCell};
 use std::collections::{RingBuf, HashMap};
-use std::io::{BufferedStream, IoResult};
+use std::io::{BufferedStream, IoResult, IoError, IoErrorKind};
 use std::io::net::ip::Port;
 use std::iter::IteratorCloneExt;
+use std::time::Duration;
 use std::mem;
 use std::fmt;
 use std::result;
 
-use io::InternalStream;
+use io::{InternalStream, Timeout};
 use message::{FrontendMessage, BackendMessage, RowDescriptionEntry};
 use message::FrontendMessage::*;
 use message::BackendMessage::*;
@@ -248,8 +250,9 @@ impl<'conn> Notifications<'conn> {
             return Ok(notification);
         }
 
-        check_desync!(self.conn.conn.borrow());
-        match try!(self.conn.conn.borrow_mut().read_message_with_notification()) {
+        let mut conn = self.conn.conn.borrow_mut();
+        check_desync!(conn);
+        match try!(conn.read_message_with_notification()) {
             NotificationResponse { pid, channel, payload } => {
                 Ok(Notification {
                     pid: pid,
@@ -260,6 +263,42 @@ impl<'conn> Notifications<'conn> {
             _ => unreachable!()
         }
     }
+
+    /// Returns the oldest pending notification
+    ///
+    /// If no notifications are pending, blocks for up to `timeout` time, after
+    /// which an `IoError` with the `TimedOut` kind is returned.
+    pub fn next_block_for(&mut self, timeout: Duration) -> Result<Notification> {
+        if let Some(notification) = self.next() {
+            return Ok(notification);
+        }
+
+        let mut conn = self.conn.conn.borrow_mut();
+        check_desync!(conn);
+
+        let end = time::now().to_timespec() + timeout;
+        loop {
+            let now = time::now().to_timespec();
+            conn.stream.set_read_timeout(Some((end - now).num_milliseconds() as u64));
+            match conn.read_one_message() {
+                Ok(Some(NotificationResponse { pid, channel, payload })) => {
+                    return Ok(Notification {
+                        pid: pid,
+                        channel: channel,
+                        payload: payload
+                    })
+                }
+                Ok(Some(_)) => unreachable!(),
+                Ok(None) => {}
+                Err(e @ IoError { kind: IoErrorKind::TimedOut, .. }) => {
+                    conn.desynchronized = false;
+                    return Err(Error::IoError(e));
+                }
+                Err(e) => return Err(Error::IoError(e)),
+            }
+
+        }
+    }
 }
 
 /// Contains information necessary to cancel queries for a session
@@ -394,19 +433,27 @@ impl InnerConnection {
         Ok(try_desync!(self, self.stream.flush()))
     }
 
-    fn read_message_with_notification(&mut self) -> IoResult<BackendMessage> {
+    fn read_one_message(&mut self) -> IoResult<Option<BackendMessage>> {
         debug_assert!(!self.desynchronized);
-        loop {
-            match try_desync!(self, self.stream.read_message()) {
-                NoticeResponse { fields } => {
-                    if let Ok(err) = DbError::new_raw(fields) {
-                        self.notice_handler.handle(err);
-                    }
-                }
-                ParameterStatus { parameter, value } => {
-                    debug!("Parameter {} = {}", parameter, value)
+        match try_desync!(self, self.stream.read_message()) {
+            NoticeResponse { fields } => {
+                if let Ok(err) = DbError::new_raw(fields) {
+                    self.notice_handler.handle(err);
                 }
-                val => return Ok(val)
+                Ok(None)
+            }
+            ParameterStatus { parameter, value } => {
+                debug!("Parameter {} = {}", parameter, value);
+                Ok(None)
+            }
+            val => Ok(Some(val))
+        }
+    }
+
+    fn read_message_with_notification(&mut self) -> IoResult<BackendMessage> {
+        loop {
+            if let Some(msg) = try!(self.read_one_message()) {
+                return Ok(msg);
             }
         }
     }

src/message.rs

@@ -1,6 +1,7 @@
 use std::io::{IoResult, IoError, OtherIoError, MemReader};
 use std::mem;
 
+use io::Timeout;
 use types::Oid;
 
 use self::BackendMessage::*;
@@ -272,9 +273,17 @@ pub trait ReadMessage {
     fn read_message(&mut self) -> IoResult<BackendMessage>;
 }
 
-impl<R: Reader> ReadMessage for R {
+impl<R: Reader+Timeout> ReadMessage for R {
     fn read_message(&mut self) -> IoResult<BackendMessage> {
-        let ident = try!(self.read_u8());
+        // The first byte read is a bit complex to make
+        // Notifications#next_block_for work.
+        let ident = self.read_u8();
+        // At this point we've got to turn off any read timeout to prevent
+        // stream desynchronization. We're assuming that if we've got the first
+        // byte, there's more stuff to follow.
+        self.set_read_timeout(None);
+        let ident = try!(ident);
+
         // subtract size of length value
         let len = try!(self.read_be_u32()) as uint - mem::size_of::<i32>();
         let mut buf = MemReader::new(try!(self.read_exact(len)));

src/types/mod.rs

@@ -307,7 +307,6 @@ pub mod array;
 pub mod range;
 #[cfg(feature = "uuid")]
 mod uuid;
-#[cfg(feature = "time")]
 mod time;
 
 /// A Postgres OID

src/types/time.rs

@@ -1,6 +1,4 @@
-extern crate time;
-
-use self::time::Timespec;
+use time::Timespec;
 use Result;
 use types::{RawFromSql, Type, RawToSql};
 use types::range::{Range, RangeBound, BoundSided, Normalizable};

tests/test.rs

@@ -8,6 +8,7 @@ extern crate openssl;
 
 use openssl::ssl::SslContext;
 use openssl::ssl::SslMethod::Sslv3;
+use std::io::{IoError, IoErrorKind};
 use std::io::timer;
 use std::time::Duration;
 
@@ -624,6 +625,46 @@ fn test_notifications_next_block() {
     }, or_panic!(notifications.next_block()));
 }
 
+#[test]
+fn test_notifications_next_block_for() {
+    let conn = or_panic!(Connection::connect("postgres://postgres@localhost", &SslMode::None));
+    or_panic!(conn.execute("LISTEN test_notifications_next_block_for", &[]));
+
+    spawn(proc() {
+        let conn = or_panic!(Connection::connect("postgres://postgres@localhost", &SslMode::None));
+        timer::sleep(Duration::milliseconds(500));
+        or_panic!(conn.execute("NOTIFY test_notifications_next_block_for, 'foo'", &[]));
+    });
+
+    let mut notifications = conn.notifications();
+    check_notification(Notification {
+        pid: 0,
+        channel: "test_notifications_next_block_for".to_string(),
+        payload: "foo".to_string()
+    }, or_panic!(notifications.next_block_for(Duration::seconds(2))));
+}
+
+#[test]
+fn test_notifications_next_block_for_timeout() {
+    let conn = or_panic!(Connection::connect("postgres://postgres@localhost", &SslMode::None));
+    or_panic!(conn.execute("LISTEN test_notifications_next_block_for_timeout", &[]));
+
+    spawn(proc() {
+        let conn = or_panic!(Connection::connect("postgres://postgres@localhost", &SslMode::None));
+        timer::sleep(Duration::seconds(2));
+        or_panic!(conn.execute("NOTIFY test_notifications_next_block_for_timeout, 'foo'", &[]));
+    });
+
+    let mut notifications = conn.notifications();
+    match notifications.next_block_for(Duration::milliseconds(500)) {
+        Err(Error::IoError(IoError { kind: IoErrorKind::TimedOut, .. })) => {},
+        Err(e) => panic!("Unexpected error {}", e),
+        Ok(_) => panic!("expected error"),
+    }
+
+    or_panic!(conn.execute("SELECT 1", &[]));
+}
+
 #[test]
 // This test is pretty sad, but I don't think there's a better way :(
 fn test_cancel_query() {