IstrSet: Less hard-coded values.

1 files changed, 15 insertions, 9 deletions

diff --git a/src/zisp/gc/IstrSet.zig b/src/zisp/gc/IstrSet.zig
index 35365d1..005c220 100644
--- a/src/zisp/gc/IstrSet.zig
+++ b/src/zisp/gc/IstrSet.zig
@@ -36,7 +36,12 @@ const IstrPtr = value.istr.IstrPtr;
 
 const Set = @This();
 
-const Bucket = [2][4]u64;
+const bucket_sectors = 2;
+const sector_u64_cnt = 4;
+
+const sector_size = sector_u64_cnt * 8;
+
+const Bucket = [bucket_sectors][sector_u64_cnt]u64;
 
 const SectorPtr = *align(8) SectorHead;
 
@@ -52,7 +57,7 @@ const SectorHead = packed union {
     }
 
     fn getIstrPtr(self: SectorPtr) IstrPtr {
-        if (self.meta.len <= 24) {
+        if (self.meta.len <= sector_size - @sizeOf(SectorHead)) {
             return @ptrCast(self);
         } else {
             return @ptrFromInt(self.bufU64()[1]);
@@ -78,7 +83,7 @@ const SectorHead = packed union {
         s: []const u8,
     ) !IstrPtr {
         self.hash = hash;
-        if (s.len <= 24) {
+        if (s.len <= sector_size - @sizeOf(SectorHead)) {
             const istr: IstrPtr = @ptrCast(self);
             istr.putStr(s);
             return istr;
@@ -90,7 +95,8 @@ const SectorHead = packed union {
     }
 
     pub fn copy(self: SectorPtr, dest: SectorPtr) void {
-        @memcpy(dest.bufU64()[0..4], self.bufU64()[0..4]);
+        const end = sector_u64_cnt;
+        @memcpy(dest.bufU64()[0..end], self.bufU64()[0..end]);
     }
 };
 
@@ -136,7 +142,7 @@ pub fn add(self: *Set, alloc: Alloc, s: []const u8) !IstrPtr {
 
     var idx = idx_init;
     const s_idx = b: while (true) : (idx = (idx + 1) & idx_mask) {
-        inline for (0..1) |si| {
+        inline for (0..bucket_sectors) |si| {
             const sec = sector(self.buckets, idx, si);
             if (sec.hash == 0) break :b si;
             if (sec.match(hash, s)) |istr| return istr;
@@ -154,8 +160,8 @@ pub fn add(self: *Set, alloc: Alloc, s: []const u8) !IstrPtr {
 
     self.used_sectors += 1;
 
-    // Remember sector count = 2 * bucket count, so 16/10 is really 8/10.
-    if (self.used_sectors >= (self.buckets.len * 16) / 10) {
+    // Resize at 80% fill rate
+    if (self.used_sectors >= (self.buckets.len * bucket_sectors * 8) / 10) {
         try self.resize(alloc);
     }
 
@@ -178,7 +184,7 @@ fn resize(self: *Set, alloc: Alloc) !void {
     const idx_mask = new_bc - 1;
 
     for (old_bs, 0..) |_, idx| {
-        inline for (0..1) |s_idx| {
+        inline for (0..bucket_sectors) |s_idx| {
             const sec = sector(old_bs, idx, s_idx);
             if (sec.hash != 0) transfer(sec, new_bs, idx_mask);
         }
@@ -191,7 +197,7 @@ fn resize(self: *Set, alloc: Alloc) !void {
 fn transfer(sec: SectorPtr, new_bs: []Bucket, idx_mask: usize) void {
     var new_idx = @as(usize, @truncate(sec.hash & idx_mask));
     while (true) : (new_idx = (new_idx + 1) & idx_mask) {
-        inline for (0..1) |new_s_idx| {
+        inline for (0..bucket_sectors) |new_s_idx| {
             const new_sec = sector(new_bs, new_idx, new_s_idx);
             if (new_sec.hash == 0) return sec.copy(new_sec);
         }