save progress

src/Concelier/__Libraries/StellaOps.Concelier.Cache.Valkey/AdvisoryCacheKeys.cs

@@ -5,6 +5,7 @@
 // Description: Key schema for Concelier Valkey cache
 // -----------------------------------------------------------------------------
 
+using System.Security.Cryptography;
 using System.Text;
 
 namespace StellaOps.Concelier.Cache.Valkey;
@@ -15,13 +16,13 @@ namespace StellaOps.Concelier.Cache.Valkey;
 /// <remarks>
 /// Key Schema:
 /// <code>
-/// advisory:{merge_hash}          → JSON(CanonicalAdvisory) - TTL based on interest_score
-/// rank:hot                       → ZSET { merge_hash: interest_score } - max 10,000 entries
-/// by:purl:{normalized_purl}      → SET { merge_hash, ... } - TTL 24h
-/// by:cve:{cve_id}                → STRING merge_hash - TTL 24h
-/// cache:stats:hits               → INCR counter
-/// cache:stats:misses             → INCR counter
-/// cache:warmup:last              → STRING ISO8601 timestamp
+/// advisory:{merge_hash}          -> JSON(CanonicalAdvisory) - TTL based on interest_score
+/// rank:hot                       -> ZSET { merge_hash: interest_score } - max 10,000 entries
+/// by:purl:{normalized_purl}      -> SET { merge_hash, ... } - TTL 24h
+/// by:cve:{cve_id}                -> STRING merge_hash - TTL 24h
+/// cache:stats:hits               -> INCR counter
+/// cache:stats:misses             -> INCR counter
+/// cache:warmup:last              -> STRING ISO8601 timestamp
 /// </code>
 /// </remarks>
 public static class AdvisoryCacheKeys
@@ -30,6 +31,7 @@ public static class AdvisoryCacheKeys
     /// Default key prefix for all cache keys.
     /// </summary>
     public const string DefaultPrefix = "concelier:";
+    public const int MaxPurlKeyLength = 500;
 
     /// <summary>
     /// Key for advisory by merge hash.
@@ -158,14 +160,20 @@ public static class AdvisoryCacheKeys
             }
         }
 
-        // Truncate if too long (Redis keys can be up to 512MB, but we want reasonable sizes)
-        const int MaxKeyLength = 500;
-        if (sb.Length > MaxKeyLength)
+        var normalizedKey = sb.ToString();
+        if (normalizedKey.Length <= MaxPurlKeyLength)
         {
-            return sb.ToString(0, MaxKeyLength);
+            return normalizedKey;
         }
 
-        return sb.ToString();
+        var hash = ComputeHash(normalizedKey);
+        var prefixLength = Math.Max(0, MaxPurlKeyLength - hash.Length - 1);
+        if (prefixLength == 0)
+        {
+            return hash;
+        }
+
+        return normalizedKey[..prefixLength] + "-" + hash;
     }
 
     /// <summary>
@@ -215,4 +223,25 @@ public static class AdvisoryCacheKeys
         }
         return null;
     }
+
+    private static string ComputeHash(string value)
+    {
+        using var sha = SHA256.Create();
+        var bytes = Encoding.UTF8.GetBytes(value);
+        var hash = sha.ComputeHash(bytes);
+        return ToLowerHex(hash);
+    }
+
+    private static string ToLowerHex(byte[] bytes)
+    {
+        const string hex = "0123456789abcdef";
+        var chars = new char[bytes.Length * 2];
+        for (var i = 0; i < bytes.Length; i++)
+        {
+            var b = bytes[i];
+            chars[i * 2] = hex[b >> 4];
+            chars[i * 2 + 1] = hex[b & 0xF];
+        }
+        return new string(chars);
+    }
 }