Caleb J. Gardner
75502da1d0
Moved more functionality to Inode instead of File. Started doing some optimization around allocation. Slight rework of ExtractionOptions.
78 lines
2.6 KiB
Zig
78 lines
2.6 KiB
Zig
const std = @import("std");
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const Mutex = std.Thread.Mutex;
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const DecompFn = @import("decomp.zig").DecompFn;
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const MetadataReader = @import("util/metadata.zig");
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const OffsetFile = @import("util/offset_file.zig");
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const TableError = error{
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InvalidIndex,
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};
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/// A two-layer metadata table.
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pub fn Table(T: anytype) type {
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return struct {
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const Self = @This();
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const VALS_PER_BLOCK = 8192 / @sizeOf(T);
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alloc: std.mem.Allocator,
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fil: OffsetFile,
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decomp: DecompFn,
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tab_start: u64,
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tab: std.AutoHashMap(u32, []T),
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values: u32,
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mut: Mutex = .{},
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pub fn init(alloc: std.mem.Allocator, fil: OffsetFile, decomp: DecompFn, tab_start: u64, values: u32) !Self {
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return .{
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.alloc = alloc,
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.fil = fil,
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.decomp = decomp,
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.tab_start = tab_start,
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.tab = .init(alloc),
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.values = values,
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};
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}
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pub fn deinit(self: *Self) void {
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var iter = self.tab.valueIterator();
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while (iter.next()) |s| {
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self.alloc.free(s.*);
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}
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self.tab.deinit();
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}
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pub fn get(self: *Self, idx: u32) !T {
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if (idx >= self.values) return TableError.InvalidIndex;
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const block_num = idx / VALS_PER_BLOCK;
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const idx_offset = idx - (block_num * VALS_PER_BLOCK);
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if (self.tab.contains(block_num)) {
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const block = self.tab.get(block_num).?;
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return block[idx_offset];
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}
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self.mut.lock();
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defer self.mut.unlock();
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// Double check in case of race condition..
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if (self.tab.contains(block_num)) {
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const block = self.tab.get(block_num).?;
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return block[idx_offset];
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}
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const is_last = (self.values - 1) / VALS_PER_BLOCK == block_num;
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const slice_size = if (is_last) self.values - (block_num * VALS_PER_BLOCK) else VALS_PER_BLOCK;
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const slice = try self.alloc.alloc(T, slice_size);
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var rdr = try self.fil.readerAt(self.tab_start + (8 * block_num), &[0]u8{});
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var offset: u64 = 0;
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try rdr.interface.readSliceEndian(u64, @ptrCast(&offset), .little);
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rdr = try self.fil.readerAt(offset, &[0]u8{});
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var meta: MetadataReader = .init(self.alloc, &rdr.interface, self.decomp);
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try meta.interface.readSliceEndian(T, @ptrCast(slice), .little);
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try self.tab.put(block_num, slice);
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return slice[idx_offset];
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}
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};
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}
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