Restart (once again)

2026-01-15 06:40:59 -06:00
parent ad7aa271ea
commit 428f938c3a
14 changed files with 395 additions and 1 deletions
@@ -0,0 +1,72 @@
+const std = @import("std");
+const Mutex = std.Thread.Mutex;
+
+const DecompMgr = @import("decomp.zig");
+const MetadataReader = @import("util/metadata.zig");
+const OffsetFile = @import("util/offset_file.zig");
+
+const TableError = error{
+    InvalidIndex,
+};
+
+pub fn Table(T: anytype) type {
+    return struct {
+        const This = @This();
+
+        const VALS_PER_BLOCK = 8192 / @sizeOf(T);
+
+        alloc: std.mem.Allocator,
+        fil: OffsetFile,
+        decomp: *DecompMgr,
+        tab_start: u64,
+
+        mut: Mutex = .{},
+
+        tab: std.AutoHashMap(u32, []T),
+        values: u32,
+
+        pub fn init(alloc: std.mem.Allocator, fil: OffsetFile, decomp: *DecompMgr, tab_start: u64, values: u32) !This {
+            return .{
+                .alloc = alloc,
+                .fil = fil,
+                .decomp = decomp,
+                .tab_start = tab_start,
+
+                .tab = .init(alloc),
+                .values = values,
+            };
+        }
+
+        pub fn deinit(self: *This) void {
+            self.tab.deinit();
+        }
+
+        pub fn get(self: *This, idx: u32) !T {
+            if (idx >= self.values) return TableError.InvalidIndex;
+            const block_num = idx / VALS_PER_BLOCK;
+            const idx_offset = idx - (block_num * VALS_PER_BLOCK);
+            if (self.tab.contains(block_num)) {
+                const block = self.tab.get(block_num).?;
+                return block[idx_offset];
+            }
+            self.mut.lock();
+            defer self.mut.unlock();
+            // Double check in case of race condition..
+            if (self.tab.contains(block_num)) {
+                const block = self.tab.get(block_num).?;
+                return block[idx_offset];
+            }
+            const is_last = (self.values - 1) / VALS_PER_BLOCK == block_num;
+            const slice_size = if (is_last) self.values - (block_num * VALS_PER_BLOCK) else VALS_PER_BLOCK;
+            const slice = try self.alloc.alloc(slice_size);
+            var rdr = try self.fil.readerAt(self.tab_start + (8 * block_num), &[0]u8{});
+            const offset: u64 = 0;
+            try rdr.interface.readSliceAll(@ptrCast(&idx_offset));
+            rdr = try self.fil.readerAt(offset, &[0]u8{});
+            var meta: MetadataReader = .init(&rdr.interface, self.decomp);
+            try meta.interface.readSliceAll(@ptrCast(slice));
+            //TODO: read & decompress block.
+            self.tab.put(block_num, slice);
+        }
+    };
+}