Remove CommandTicket to avoid Vec allocation

src/exec/command.rs

@@ -0,0 +1,98 @@
+// Copyright (c) 2017 fd developers
+// Licensed under the Apache License, Version 2.0
+// <LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0>
+// or the MIT license <LICENSE-MIT or http://opensource.org/licenses/MIT>,
+// at your option. All files in the project carrying such
+// notice may not be copied, modified, or distributed except
+// according to those terms.
+
+use std::process::Command;
+use std::sync::{Arc, Mutex};
+use std::io;
+
+/// Executes a command.
+#[cfg(not(unix))]
+pub fn execute_command(mut cmd: Command, out_perm: Arc<Mutex<()>>) {
+    use std::process::Stdio;
+    use std::io::Write;
+
+    // Spawn the supplied command.
+    let output = cmd.stdout(Stdio::piped()).stderr(Stdio::piped()).output();
+
+    // Then wait for the command to exit, if it was spawned.
+    match output {
+        Ok(output) => {
+            // While this lock is active, this thread will be the only thread allowed
+            // to write it's outputs.
+            let _lock = out_perm.lock().unwrap();
+
+            let stdout = io::stdout();
+            let stderr = io::stderr();
+
+            let _ = stdout.lock().write_all(&output.stdout);
+            let _ = stderr.lock().write_all(&output.stderr);
+        }
+        Err(why) => eprintln!("fd: exec error: {}", why),
+    }
+}
+
+/// Executes a command.
+#[cfg(all(unix))]
+pub fn execute_command(mut cmd: Command, out_perm: Arc<Mutex<()>>) {
+    use libc::{close, dup2, pipe, STDERR_FILENO, STDOUT_FILENO};
+    use std::fs::File;
+    use std::os::unix::process::CommandExt;
+    use std::os::unix::io::FromRawFd;
+
+    // Initial a pair of pipes that will be used to
+    // pipe the std{out,err} of the spawned process.
+    let mut stdout_fds = [0; 2];
+    let mut stderr_fds = [0; 2];
+
+    unsafe {
+        pipe(stdout_fds.as_mut_ptr());
+        pipe(stderr_fds.as_mut_ptr());
+    }
+
+    // Configure the pipes accordingly in the child.
+    let child = cmd.before_exec(move || unsafe {
+        // Redirect the child's std{out,err} to the write ends of our pipe.
+        dup2(stdout_fds[1], STDOUT_FILENO);
+        dup2(stderr_fds[1], STDERR_FILENO);
+
+        // Close all the fds we created here, so EOF will be sent when the program exits.
+        close(stdout_fds[0]);
+        close(stdout_fds[1]);
+        close(stderr_fds[0]);
+        close(stderr_fds[1]);
+        Ok(())
+    }).spawn();
+
+    // Open the read end of the pipes as `File`s.
+    let (mut pout, mut perr) = unsafe {
+        // Close the write ends of the pipes in the parent
+        close(stdout_fds[1]);
+        close(stderr_fds[1]);
+        (
+            // But create files from the read ends.
+            File::from_raw_fd(stdout_fds[0]),
+            File::from_raw_fd(stderr_fds[0]),
+        )
+    };
+
+    match child {
+        Ok(mut child) => {
+            let _ = child.wait();
+
+            // Create a lock to ensure that this thread has exclusive access to writing.
+            let _lock = self.out_perm.lock().unwrap();
+
+            // And then write the outputs of the process until EOF is sent to each file.
+            let stdout = io::stdout();
+            let stderr = io::stderr();
+            let _ = io::copy(&mut pout, &mut stdout.lock());
+            let _ = io::copy(&mut perr, &mut stderr.lock());
+        }
+        Err(why) => eprintln!("fd: exec error: {}", why),
+    }
+}

src/exec/job.rs

@@ -34,6 +34,6 @@ pub fn job(
         // Drop the lock so that other threads can read from the the receiver.
         drop(lock);
         // Generate a command and execute it.
-        cmd.generate(&value, Arc::clone(&out_perm)).then_execute();
+        cmd.generate_and_execute(&value, Arc::clone(&out_perm));
     }
 }

src/exec/mod.rs

@@ -7,27 +7,28 @@
 // according to those terms.
 
 // TODO: Possible optimization could avoid pushing characters on a buffer.
-mod ticket;
+mod command;
 mod token;
 mod job;
 mod input;
 
 use std::borrow::Cow;
 use std::path::Path;
+use std::process::Command;
 use std::sync::{Arc, Mutex};
 
 use regex::Regex;
 
 use self::input::{basename, dirname, remove_extension};
-use self::ticket::CommandTicket;
+use self::command::execute_command;
 use self::token::Token;
 pub use self::job::job;
 
 /// Contains a collection of `TokenizedArgument`s that are utilized to generate command strings.
 ///
 /// The arguments are a representation of the supplied command template, and are meant to be coupled
-/// with an input in order to generate a command. The `generate()` method will be used to generate
-/// a command and obtain a ticket for executing that command.
+/// with an input in order to generate a command. The `generate_and_execute()` method will be used
+/// to generate a command and execute it.
 #[derive(Debug, Clone, PartialEq)]
 pub struct TokenizedCommand {
     args: Vec<TokenizedArgument>,
@@ -74,7 +75,7 @@ impl TokenizedCommand {
         S: AsRef<str>,
     {
         lazy_static! {
-            static ref PLACEHOLDER: Regex = Regex::new(r"\{(/?\.?|//)\}").unwrap();
+            static ref PLACEHOLDER_PATTERN: Regex = Regex::new(r"\{(/?\.?|//)\}").unwrap();
         }
 
         let mut args = Vec::new();
@@ -86,7 +87,7 @@ impl TokenizedCommand {
             let mut tokens = Vec::new();
             let mut start = 0;
 
-            for placeholder in PLACEHOLDER.find_iter(arg) {
+            for placeholder in PLACEHOLDER_PATTERN.find_iter(arg) {
                 // Leading text before the placeholder.
                 if placeholder.start() > start {
                     tokens.push(Token::Text(arg[start..placeholder.start()].to_owned()));
@@ -128,24 +129,23 @@ impl TokenizedCommand {
         TokenizedCommand { args: args }
     }
 
-    /// Generates a ticket that is required to execute the generated command.
+    /// Generates and executes a command.
     ///
-    /// Using the internal `args` field, and a supplied `input` variable, arguments will be
-    /// collected in a Vec. Once all arguments have been processed, the Vec will be wrapped
-    /// within a `CommandTicket`, which will be responsible for executing the command.
-    pub fn generate(&self, input: &Path, out_perm: Arc<Mutex<()>>) -> CommandTicket {
+    /// Using the internal `args` field, and a supplied `input` variable, a `Command` will be
+    /// build. Once all arguments have been processed, the command is executed.
+    pub fn generate_and_execute(&self, input: &Path, out_perm: Arc<Mutex<()>>) {
         let input = input
             .strip_prefix(".")
             .unwrap_or(input)
             .to_string_lossy()
             .into_owned();
 
-        let mut args = Vec::with_capacity(self.args.len());
-        for arg in &self.args {
-            args.push(arg.generate(&input));
+        let mut cmd = Command::new(self.args[0].generate(&input).as_ref());
+        for arg in &self.args[1..] {
+            cmd.arg(arg.generate(&input).as_ref());
         }
 
-        CommandTicket::new(args, out_perm)
+        execute_command(cmd, out_perm)
     }
 }
 

src/exec/ticket.rs

@@ -1,126 +0,0 @@
-// Copyright (c) 2017 fd developers
-// Licensed under the Apache License, Version 2.0
-// <LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0>
-// or the MIT license <LICENSE-MIT or http://opensource.org/licenses/MIT>,
-// at your option. All files in the project carrying such
-// notice may not be copied, modified, or distributed except
-// according to those terms.
-
-use std::process::Command;
-use std::sync::{Arc, Mutex};
-use std::io;
-
-/// A state that offers access to executing a generated command.
-///
-/// The ticket holds the collection of arguments of a command to be executed.
-pub struct CommandTicket {
-    args: Vec<String>,
-    out_perm: Arc<Mutex<()>>,
-}
-
-impl CommandTicket {
-    pub fn new<I, S>(args: I, out_perm: Arc<Mutex<()>>) -> CommandTicket
-    where
-        I: IntoIterator<Item = S>,
-        S: AsRef<str>,
-    {
-        CommandTicket {
-            args: args.into_iter().map(|x| x.as_ref().to_owned()).collect(),
-            out_perm: out_perm,
-        }
-    }
-
-    /// Executes the command stored within the ticket.
-    #[cfg(not(unix))]
-    pub fn then_execute(self) {
-        use std::process::Stdio;
-        use std::io::Write;
-
-        // Spawn the supplied command.
-        let cmd = Command::new(&self.args[0])
-            .args(&self.args[1..])
-            .stdout(Stdio::piped())
-            .stderr(Stdio::piped())
-            .output();
-
-        // Then wait for the command to exit, if it was spawned.
-        match cmd {
-            Ok(output) => {
-                // While this lock is active, this thread will be the only thread allowed
-                // to write it's outputs.
-                let _lock = self.out_perm.lock().unwrap();
-
-                let stdout = io::stdout();
-                let stderr = io::stderr();
-
-                let _ = stdout.lock().write_all(&output.stdout);
-                let _ = stderr.lock().write_all(&output.stderr);
-            }
-            Err(why) => eprintln!("fd: exec error: {}", why),
-        }
-    }
-
-    #[cfg(all(unix))]
-    pub fn then_execute(self) {
-        use libc::{close, dup2, pipe, STDERR_FILENO, STDOUT_FILENO};
-        use std::fs::File;
-        use std::os::unix::process::CommandExt;
-        use std::os::unix::io::FromRawFd;
-
-        // Initial a pair of pipes that will be used to
-        // pipe the std{out,err} of the spawned process.
-        let mut stdout_fds = [0; 2];
-        let mut stderr_fds = [0; 2];
-
-        unsafe {
-            pipe(stdout_fds.as_mut_ptr());
-            pipe(stderr_fds.as_mut_ptr());
-        }
-
-        // Spawn the supplied command.
-        let cmd = Command::new(&self.args[0])
-            .args(&self.args[1..])
-            // Configure the pipes accordingly in the child.
-            .before_exec(move || unsafe {
-                // Redirect the child's std{out,err} to the write ends of our pipe.
-                dup2(stdout_fds[1], STDOUT_FILENO);
-                dup2(stderr_fds[1], STDERR_FILENO);
-
-                // Close all the fds we created here, so EOF will be sent when the program exits.
-                close(stdout_fds[0]);
-                close(stdout_fds[1]);
-                close(stderr_fds[0]);
-                close(stderr_fds[1]);
-                Ok(())
-            })
-            .spawn();
-
-        // Open the read end of the pipes as `File`s.
-        let (mut pout, mut perr) = unsafe {
-            // Close the write ends of the pipes in the parent
-            close(stdout_fds[1]);
-            close(stderr_fds[1]);
-            (
-                // But create files from the read ends.
-                File::from_raw_fd(stdout_fds[0]),
-                File::from_raw_fd(stderr_fds[0]),
-            )
-        };
-
-        match cmd {
-            Ok(mut child) => {
-                let _ = child.wait();
-
-                // Create a lock to ensure that this thread has exclusive access to writing.
-                let _lock = self.out_perm.lock().unwrap();
-
-                // And then write the outputs of the process until EOF is sent to each file.
-                let stdout = io::stdout();
-                let stderr = io::stderr();
-                let _ = io::copy(&mut pout, &mut stdout.lock());
-                let _ = io::copy(&mut perr, &mut stderr.lock());
-            }
-            Err(why) => eprintln!("fd: exec error: {}", why),
-        }
-    }
-}