Go back to memcmp() for companing OIDs, for performance reasons

Uncommon · Uncommon · commit 738ca6016f50 · 2024-04-08T15:34:13.000-06:00
diff --git a/Xit/Repository/OID.swift b/Xit/Repository/OID.swift
@@ -170,13 +170,17 @@ extension GitOID: CustomStringConvertible
   public var description: String { sha }
 }
 
+let oidSize = 20
+
 public func == (left: GitOID, right: GitOID) -> Bool
 {
   left.withUnsafeOID {
     (leftOID) in
     right.withUnsafeOID {
       (rightOID) in
-      git_oid_equal(leftOID, rightOID) != 0
+      // git_oid_equal() is slowed down by the use of git_oid_size(), which isn't
+      // even needed with SHA256 support turned off
+      memcmp(leftOID, rightOID, oidSize) == 0
     }
   }
 }

Original file line number	Diff line number	Diff line change
`@@ -170,13 +170,17 @@ extension GitOID: CustomStringConvertible`
`170`	`170`	`public var description: String { sha }`
`171`	`171`	`}`
`172`	`172`
	`173`	`+let oidSize = 20`
	`174`	`+`
`173`	`175`	`public func == (left: GitOID, right: GitOID) -> Bool`
`174`	`176`	`{`
`175`	`177`	`left.withUnsafeOID {`
`176`	`178`	`(leftOID) in`
`177`	`179`	`right.withUnsafeOID {`
`178`	`180`	`(rightOID) in`
`179`		`- git_oid_equal(leftOID, rightOID) != 0`
	`181`	`+ // git_oid_equal() is slowed down by the use of git_oid_size(), which isn't`
	`182`	`+ // even needed with SHA256 support turned off`
	`183`	`+ memcmp(leftOID, rightOID, oidSize) == 0`
`180`	`184`	`}`
`181`	`185`	`}`
`182`	`186`	`}`