feat: hash length configuration

Add hash-length configuration option which controls the length of the
hash components.

Fixes #97

CHANGELOG.md

@@ -1,8 +1,9 @@
 # Changelog
 
-## 2.3.1
+## 2.4.0
 
 - Fix cache key stability.
+- Add `hash-length` option, which provides control over the length of hash components.
 
 ## 2.3.0
 

README.md

@@ -65,6 +65,11 @@ sensible defaults.
     # Useful for jobs where the matrix is additive e.g. additional Cargo features.
     # default: "true"
     save-if: ""
+
+    # The length of the hash components used to identify the cache.
+    # If `0`, the full hash is used."
+    # default: "0"
+    hash-length: ""
 ```
 
 Further examples are available in the [.github/workflows](./.github/workflows/) directory.

action.yml

@@ -36,6 +36,10 @@ inputs:
     description: "Determiners whether the cache should be saved. If `false`, the cache is only restored."
     required: false
     default: "true"
+  hash-length:
+    description: "The length of the hash components used to identify the cache. If `0`, the full hash is used."
+    required: false
+    default: "0"
 outputs:
   cache-hit:
     description: "A boolean value that indicates an exact match was found."

dist/restore/index.js

@@ -60064,6 +60064,15 @@ class CacheConfig {
                 .map((w) => new Workspace(w.root, w.target));
             return self;
         }
+        let hashLenInput = lib_core.getInput("hash-length");
+        let hashLen = 0;
+        if (hashLenInput) {
+            hashLen = parseInt(hashLenInput, 10);
+            if (isNaN(hashLen)) {
+                lib_core.error(`Invalid hash-length: "${hashLenInput}" ignoring`);
+                hashLen = 0;
+            }
+        }
         // Construct key prefix:
         // This uses either the `shared-key` input,
         // or the `key` input combined with the `job` key.
@@ -60111,7 +60120,7 @@ class CacheConfig {
             }
         }
         self.keyEnvs = keyEnvs;
-        key += `-${hasher.digest("hex")}`;
+        key += `-${digest(hasher, hashLen)}`;
         self.restoreKey = key;
         // Construct the lockfiles portion of the key:
         // This considers all the files found via globbing for various manifests
@@ -60140,7 +60149,7 @@ class CacheConfig {
                 hasher.update(chunk);
             }
         }
-        let lockHash = hasher.digest("hex");
+        let lockHash = digest(hasher, hashLen);
         self.keyFiles = keyFiles;
         key += `-${lockHash}`;
         self.cacheKey = key;
@@ -60203,6 +60212,21 @@ class CacheConfig {
 function isCacheUpToDate() {
     return core.getState(STATE_CONFIG) === "";
 }
+/**
+ * Returns a hex digest of the given hasher.
+ * If `length` is `0`, the full digest is returned.
+ * Otherwise, the digest is truncated to the given length.
+ *
+ * @param hasher The hasher to digest.
+ * @param length The length of the digest.
+ * @returns The hex digest.
+ */
+function digest(hasher, length) {
+    if (length == 0) {
+        return hasher.digest("hex");
+    }
+    return hasher.digest("hex").substring(0, length);
+}
 async function getRustVersion() {
     const stdout = await getCmdOutput("rustc", ["-vV"]);
     let splits = stdout

dist/save/index.js

@@ -60064,6 +60064,15 @@ class CacheConfig {
                 .map((w) => new Workspace(w.root, w.target));
             return self;
         }
+        let hashLenInput = core.getInput("hash-length");
+        let hashLen = 0;
+        if (hashLenInput) {
+            hashLen = parseInt(hashLenInput, 10);
+            if (isNaN(hashLen)) {
+                core.error(`Invalid hash-length: "${hashLenInput}" ignoring`);
+                hashLen = 0;
+            }
+        }
         // Construct key prefix:
         // This uses either the `shared-key` input,
         // or the `key` input combined with the `job` key.
@@ -60111,7 +60120,7 @@ class CacheConfig {
             }
         }
         self.keyEnvs = keyEnvs;
-        key += `-${hasher.digest("hex")}`;
+        key += `-${digest(hasher, hashLen)}`;
         self.restoreKey = key;
         // Construct the lockfiles portion of the key:
         // This considers all the files found via globbing for various manifests
@@ -60140,7 +60149,7 @@ class CacheConfig {
                 hasher.update(chunk);
             }
         }
-        let lockHash = hasher.digest("hex");
+        let lockHash = digest(hasher, hashLen);
         self.keyFiles = keyFiles;
         key += `-${lockHash}`;
         self.cacheKey = key;
@@ -60203,6 +60212,21 @@ class CacheConfig {
 function isCacheUpToDate() {
     return core.getState(STATE_CONFIG) === "";
 }
+/**
+ * Returns a hex digest of the given hasher.
+ * If `length` is `0`, the full digest is returned.
+ * Otherwise, the digest is truncated to the given length.
+ *
+ * @param hasher The hasher to digest.
+ * @param length The length of the digest.
+ * @returns The hex digest.
+ */
+function digest(hasher, length) {
+    if (length == 0) {
+        return hasher.digest("hex");
+    }
+    return hasher.digest("hex").substring(0, length);
+}
 async function getRustVersion() {
     const stdout = await getCmdOutput("rustc", ["-vV"]);
     let splits = stdout

src/config.ts

@@ -56,6 +56,16 @@ export class CacheConfig {
       return self;
     }
 
+    let hashLenInput = core.getInput("hash-length");
+    let hashLen = 0;
+    if (hashLenInput) {
+      hashLen = parseInt(hashLenInput, 10);
+      if (isNaN(hashLen)) {
+        core.error(`Invalid hash-length: "${hashLenInput}" ignoring`);
+        hashLen = 0;
+      }
+    }
+
     // Construct key prefix:
     // This uses either the `shared-key` input,
     // or the `key` input combined with the `job` key.
@@ -114,7 +124,7 @@ export class CacheConfig {
 
     self.keyEnvs = keyEnvs;
 
-    key += `-${hasher.digest("hex")}`;
+    key += `-${digest(hasher, hashLen)}`;
 
     self.restoreKey = key;
 
@@ -153,7 +163,7 @@ export class CacheConfig {
         hasher.update(chunk);
       }
     }
-    let lockHash = hasher.digest("hex");
+    let lockHash = digest(hasher, hashLen);
 
     self.keyFiles = keyFiles;
 
@@ -226,6 +236,22 @@ export function isCacheUpToDate(): boolean {
   return core.getState(STATE_CONFIG) === "";
 }
 
+/**
+ * Returns a hex digest of the given hasher.
+ * If `length` is `0`, the full digest is returned.
+ * Otherwise, the digest is truncated to the given length.
+ *
+ * @param hasher The hasher to digest.
+ * @param length The length of the digest.
+ * @returns The hex digest.
+ */
+function digest(hasher: crypto.Hash, length: number): string {
+  if (length == 0) {
+    return hasher.digest("hex");
+  }
+  return hasher.digest("hex").substring(0, length);
+}
+
 interface RustVersion {
   host: string;
   release: string;