Use a shared cargo directory

This will drastically improve:
- Speed: Not everything will need to be recompiled once making a
minor change to a script.

- Size: Will avoid downloading and building dependencies for each minor
  edit.

Author: fornwall

src/consts.rs

@@ -125,9 +125,12 @@ where F: FnMut(&str, usize) -> T, T: 'static {
 }
 "#;
 
-/// Substitution for the identifier-safe name of the script.
+/// Substitution for the identifier-safe package name of the script.
 pub const MANI_NAME_SUB: &str = "name";
 
+/// Substitution for the identifier-safe bin name of the script.
+pub const MANI_BIN_NAME_SUB: &str = "bin_name";
+
 /// Substitution for the filesystem-safe name of the script.
 pub const MANI_FILE_SUB: &str = "file";
 
@@ -142,7 +145,7 @@ authors = ["Anonymous"]
 edition = "2018"
 
 [[bin]]
-name = "#{name}"
+name = "#{bin_name}"
 path = "#{file}.rs"
 "##;
 
@@ -161,7 +164,7 @@ When generating a package's unique ID, how many hex nibbles of the digest should
 
 The largest meaningful value is `40`.
 */
-pub const ID_DIGEST_LEN_MAX: usize = 16;
+pub const ID_DIGEST_LEN_MAX: usize = 24;
 
 /**
 How old can stuff in the cache be before we automatically clear it out?

src/main.rs

@@ -5,11 +5,6 @@ extern crate lazy_static;
 #[macro_use]
 extern crate log;
 
-/**
-If this is set to `true`, the digests used for package IDs will be replaced with "stub" to make testing a bit easier.  Obviously, you don't want this `true` for release...
-*/
-const STUB_HASHES: bool = false;
-
 /**
 If this is set to `false`, then code that automatically deletes stuff *won't*.
 */
@@ -637,9 +632,6 @@ This represents what to do with the input provided by the user.
 */
 #[derive(Debug)]
 struct InputAction {
-    /// Compile the input into a fresh executable?
-    compile: bool,
-
     /// Always show cargo output?
     cargo_output: bool,
 
@@ -737,13 +729,6 @@ struct PackageMetadata {
     script_hash: String,
 }
 
-impl PackageMetadata {
-    pub fn sha1_hash(&self) -> String {
-        // Yes, I *do* feel dirty for doing it like this.  :D
-        hash_str(&format!("{:?}", self))
-    }
-}
-
 /**
 For the given input, this constructs the package metadata and checks the cache to see what should be done.
 */
@@ -753,28 +738,26 @@ fn decide_action_for(
     prelude: Vec<String>,
     args: &Args,
 ) -> MainResult<InputAction> {
+    let input_id = {
+        let deps_iter = deps.iter().map(|&(ref n, ref v)| (n as &str, v as &str));
+        // Again, also fucked if we can't work this out.
+        input.compute_id(deps_iter).unwrap()
+    };
+    info!("id: {:?}", input_id);
+
     let (pkg_path, using_cache) = args
         .pkg_path
         .as_ref()
         .map(|p| (p.into(), false))
         .unwrap_or_else(|| {
             // This can't fail.  Seriously, we're *fucked* if we can't work this out.
             let cache_path = platform::generated_projects_cache_path().unwrap();
-
-            let id = {
-                let deps_iter = deps.iter().map(|&(ref n, ref v)| (n as &str, v as &str));
-
-                // Again, also fucked if we can't work this out.
-                input.compute_id(deps_iter).unwrap()
-            };
-            info!("id: {:?}", id);
-
-            (cache_path.join(&id), true)
+            (cache_path.join(&input_id), true)
         });
     info!("pkg_path: {:?}", pkg_path);
     info!("using_cache: {:?}", using_cache);
 
-    let (mani_str, script_str) = manifest::split_input(input, &deps, &prelude)?;
+    let (mani_str, script_str) = manifest::split_input(input, &deps, &prelude, &input_id)?;
 
     // Forcibly override some flags based on build kind.
     let (debug, force) = match args.build_kind {
@@ -806,7 +789,6 @@ fn decide_action_for(
     info!("input_meta: {:?}", input_meta);
 
     let mut action = InputAction {
-        compile: force,
         cargo_output: args.cargo_output,
         force_compile: force,
         emit_metadata: true,
@@ -832,38 +814,29 @@ fn decide_action_for(
 
     // If we were told to only generate the package, we need to stop *now*
     if args.gen_pkg_only {
-        bail!(compile: false, execute: false)
+        bail!(execute: false)
     }
 
     // If we're not doing a regular build, stop.
     match action.build_kind {
         BuildKind::Normal => (),
         BuildKind::Test | BuildKind::Bench => {
             info!("not recompiling because: user asked for test/bench");
-            bail!(compile: false, force_compile: false)
+            bail!(force_compile: false)
         }
     }
 
-    let cache_meta = match get_pkg_metadata(&action.pkg_path) {
-        Ok(meta) => meta,
+    action.old_metadata = match get_pkg_metadata(&action.pkg_path) {
+        Ok(meta) => Some(meta),
         Err(err) => {
             info!(
                 "recompiling since failed to load metadata: {}",
                 err.to_string()
             );
-            bail!(compile: true)
+            None
         }
     };
 
-    if cache_meta != action.metadata {
-        info!("recompiling because: metadata did not match");
-        debug!("input metadata: {:?}", action.metadata);
-        debug!("cache metadata: {:?}", cache_meta);
-        bail!(old_metadata: Some(cache_meta), compile: true)
-    }
-
-    action.old_metadata = Some(cache_meta);
-
     Ok(action)
 }
 
@@ -1063,7 +1036,7 @@ impl<'a> Input<'a> {
         };
 
         match *self {
-            File(name, path, _, _) => {
+            File(_, path, _, _) => {
                 let mut hasher = Sha1::new();
 
                 // Hash the path to the script.
@@ -1072,10 +1045,7 @@ impl<'a> Input<'a> {
                 digest.truncate(consts::ID_DIGEST_LEN_MAX);
 
                 let mut id = OsString::new();
-                id.push("file-");
-                id.push(name);
-                id.push("-");
-                id.push(if STUB_HASHES { "stub" } else { &*digest });
+                id.push(&*digest );
                 Ok(id)
             }
             Expr(content, template) => {
@@ -1090,8 +1060,7 @@ impl<'a> Input<'a> {
                 digest.truncate(consts::ID_DIGEST_LEN_MAX);
 
                 let mut id = OsString::new();
-                id.push("expr-");
-                id.push(if STUB_HASHES { "stub" } else { &*digest });
+                id.push(&*digest);
                 Ok(id)
             }
             Loop(content, count) => {
@@ -1106,8 +1075,7 @@ impl<'a> Input<'a> {
                 digest.truncate(consts::ID_DIGEST_LEN_MAX);
 
                 let mut id = OsString::new();
-                id.push("loop-");
-                id.push(if STUB_HASHES { "stub" } else { &*digest });
+                id.push(&*digest);
                 Ok(id)
             }
         }
@@ -1176,12 +1144,11 @@ fn cargo(
         cmd.arg("--color").arg("always");
     }
 
-    let script_specific_binary_cache = format!(
-        "{}/{}",
+    let cargo_target_dir = format!(
+        "{}",
         platform::binary_cache_path()?.display(),
-        meta.sha1_hash()
     );
-    cmd.env("CARGO_TARGET_DIR", script_specific_binary_cache);
+    cmd.env("CARGO_TARGET_DIR", cargo_target_dir);
 
     // Block `--release` on `bench`.
     if !meta.debug && cmd_name != "bench" {

src/manifest.rs

@@ -12,6 +12,7 @@ use crate::consts;
 use crate::error::{MainError, MainResult};
 use crate::templates;
 use crate::Input;
+use std::ffi::OsString;
 
 lazy_static! {
     static ref RE_SHORT_MANIFEST: Regex =
@@ -41,6 +42,7 @@ pub fn split_input(
     input: &Input,
     deps: &[(String, String)],
     prelude_items: &[String],
+    input_id: &OsString,
 ) -> MainResult<(String, String)> {
     let template_buf;
     let (part_mani, source, template, sub_prelude) = match *input {
@@ -98,7 +100,7 @@ pub fn split_input(
     info!("part_mani: {:?}", part_mani);
 
     // It's-a mergin' time!
-    let def_mani = default_manifest(input)?;
+    let def_mani = default_manifest(input, input_id)?;
     let dep_mani = deps_manifest(deps)?;
 
     let mani = merge_manifest(def_mani, part_mani)?;
@@ -116,9 +118,10 @@ pub fn split_input(
 
 #[test]
 fn test_split_input() {
+    let input_id = OsString::from("input_id");
     macro_rules! si {
         ($i:expr) => {
-            split_input(&$i, &[], &[]).ok()
+            split_input(&$i, &[], &[], &input_id).ok()
         };
     }
 
@@ -136,7 +139,7 @@ fn test_split_input() {
         si!(f(r#"fn main() {}"#)),
         r!(
             r#"[[bin]]
-name = "n"
+name = "n_input_id"
 path = "n.rs"
 
 [dependencies]
@@ -159,7 +162,7 @@ fn main() {}
 "#)),
         r!(
             r#"[[bin]]
-name = "n"
+name = "n_input_id"
 path = "n.rs"
 
 [dependencies]
@@ -185,7 +188,7 @@ fn main() {}
 "#)),
         r!(
             r#"[[bin]]
-name = "n"
+name = "n_input_id"
 path = "n.rs"
 
 [dependencies]
@@ -211,7 +214,7 @@ fn main() {}
 "#)),
         r!(
             r#"[[bin]]
-name = "n"
+name = "n_input_id"
 path = "n.rs"
 
 [dependencies]
@@ -237,7 +240,7 @@ fn main() {}
 "#)),
         r!(
             r#"[[bin]]
-name = "n"
+name = "n_input_id"
 path = "n.rs"
 
 [dependencies]
@@ -271,7 +274,7 @@ fn main() {}
 "#)),
         r!(
             r#"[[bin]]
-name = "n"
+name = "n_input_id"
 path = "n.rs"
 
 [dependencies]
@@ -1015,11 +1018,13 @@ time = "*"
 /**
 Generates a default Cargo manifest for the given input.
 */
-fn default_manifest(input: &Input) -> MainResult<toml::value::Table> {
+fn default_manifest(input: &Input, input_id: &OsString) -> MainResult<toml::value::Table> {
     let mani_str = {
         let pkg_name = input.package_name();
-        let mut subs = HashMap::with_capacity(2);
+        let bin_name = format!("{}_{}", &*pkg_name, input_id.to_str().unwrap());
+        let mut subs = HashMap::with_capacity(3);
         subs.insert(consts::MANI_NAME_SUB, &*pkg_name);
+        subs.insert(consts::MANI_BIN_NAME_SUB, &*bin_name);
         subs.insert(consts::MANI_FILE_SUB, &input.safe_name()[..]);
         templates::expand(consts::DEFAULT_MANIFEST, &subs)?
     };