add command cache key

Author: Shourya742

src/bootstrap/src/utils/exec.rs

@@ -55,6 +55,14 @@ impl OutputMode {
     }
 }
 
+#[derive(Clone, Debug, PartialEq, Eq, Hash, Default)]
+pub struct CommandCacheKey {
+    program: String,
+    args: Vec<String>,
+    envs: Vec<(String, String)>,
+    cwd: Option<PathBuf>,
+}
+
 /// Wrapper around `std::process::Command`.
 ///
 /// By default, the command will exit bootstrap if it fails.
@@ -225,6 +233,15 @@ impl<'a> BootstrapCommand {
             self.env("TERM", "xterm").args(["--color", "always"]);
         }
     }
+
+    pub fn cache_key(&self) -> CommandCacheKey {
+        CommandCacheKey {
+            program: self.program.clone(),
+            args: self.args.clone(),
+            envs: self.envs.clone(),
+            cwd: self.cwd.clone(),
+        }
+    }
 }
 
 impl Debug for BootstrapCommand {

src/bootstrap/src/utils/execution_context.rs

@@ -3,13 +3,16 @@
 //! This module provides the [`ExecutionContext`] type, which holds global configuration
 //! relevant during the execution of commands in bootstrap. This includes dry-run
 //! mode, verbosity level, and behavior on failure.
+#![allow(warnings)]
+use std::collections::HashMap;
 use std::panic::Location;
 use std::process::Child;
 use std::sync::{Arc, Mutex};
 
 use crate::core::config::DryRun;
 #[cfg(feature = "tracing")]
 use crate::trace_cmd;
+use crate::utils::exec::CommandCacheKey;
 use crate::{BehaviorOnFailure, BootstrapCommand, CommandOutput, OutputMode, exit};
 
 #[derive(Clone, Default)]
@@ -18,6 +21,26 @@ pub struct ExecutionContext {
     verbose: u8,
     pub fail_fast: bool,
     delayed_failures: Arc<Mutex<Vec<String>>>,
+    command_cache: Arc<CommandCache>,
+}
+
+#[derive(Default)]
+pub struct CommandCache {
+    cache: Mutex<HashMap<CommandCacheKey, CommandOutput>>,
+}
+
+impl CommandCache {
+    pub fn new() -> Self {
+        Self { cache: Mutex::new(HashMap::new()) }
+    }
+
+    pub fn get(&self, key: &CommandCacheKey) -> Option<CommandOutput> {
+        self.cache.lock().unwrap().get(key).cloned()
+    }
+
+    pub fn insert(&self, key: CommandCacheKey, output: CommandOutput) {
+        self.cache.lock().unwrap().insert(key, output);
+    }
 }
 
 impl ExecutionContext {
@@ -123,7 +146,24 @@ impl ExecutionContext {
         stdout: OutputMode,
         stderr: OutputMode,
     ) -> CommandOutput {
-        self.start(command, stdout, stderr).wait_for_output(self)
+        let cache_key = command.cache_key();
+
+        if let Some(cached_output) = self.command_cache.get(&cache_key) {
+            command.mark_as_executed();
+            if self.dry_run() && !command.run_always {
+                return CommandOutput::default();
+            }
+            self.verbose(|| println!("Cache hit: {:?}", command));
+            return cached_output;
+        }
+
+        let output = self.start(command, stdout, stderr).wait_for_output(self);
+
+        if output != CommandOutput::default() {
+            self.command_cache.insert(cache_key, output.clone());
+        }
+
+        output
     }
 
     fn fail(&self, message: &str, output: CommandOutput) -> ! {