Finished (?) data reader

src/reader/data.zig

@@ -5,6 +5,11 @@ const FragEntry = @import("../fragment.zig").FragEntry;
 const BlockSize = @import("../inode/file.zig").BlockSize;
 const Compression = @import("../superblock.zig").Compression;
 
+const DataReaderError = error{
+    EOF,
+    ThreadPoolNotSet,
+};
+
 pub fn DataReader(comptime T: type) type {
     return struct {
         const Self = @This();
@@ -77,11 +82,14 @@ pub fn DataReader(comptime T: type) type {
             );
             @memcpy(self.frag, block[offset..]);
         }
+
         pub fn setPool(self: *Self, pool: *std.Thread.Pool) void {
             self.pool = pool;
         }
 
         fn blockAt(self: Self, idx: u32) ![]u8 {
+            if (self.frag.len > 0 and idx == self.sizes.len) return self.frag;
+            if (idx >= self.sizes.len) return DataReaderError.InvalidIndex;
             const size = if (idx == self.sizes.len - 1 and self.frag.len == 0) {
                 self.file_size % self.block_size;
             } else {
@@ -107,20 +115,135 @@ pub fn DataReader(comptime T: type) type {
             return block;
         }
 
+        fn numBlocks(self: Self) usize {
+            var out = self.sizes.len;
+            if (self.frag.len > 0) out += 1;
+            return out;
+        }
+
         pub fn read(self: *Self, buf: []u8) !usize {
             var cur_red: usize = 0;
+            var to_read: usize = 0;
             while (cur_red < buf.len) {
                 if (self.read_offset >= self.read_block.len) {
-                    //TODO:
+                    if (self.read_idx == self.sizes.len or (self.frag.len == 0 and self.read_idx == self.sizes.len - 1)) {
+                        self.block_size = self.file_size % self.block_size;
+                    }
+                    self.read_block = self.blockAt(self.read_idx) catch |err| {
+                        if (err == DataReaderError.EOF) return cur_red;
+                        return err;
+                    };
+                    self.read_idx += 1;
                 }
-                //TODO:
+                to_read = @min(buf.len - cur_red, self.block_size - self.read_offset);
+                @memcpy(buf[cur_red .. cur_red + to_read], self.read_block[self.read_offset .. self.read_offset + to_read]);
+                cur_red += to_read;
+                self.read_offset += to_read;
             }
             return cur_red;
         }
 
         /// Write the entire file's contents to the writer.
         /// If availble, pwrite will be used.
-        /// If a thread pool is not set via setPool, one is created based on cpu thread count.
-        pub fn writeTo(self: Self, writer: anytype) !usize {}
+        pub fn writeTo(self: Self, writer: anytype) !usize {
+            if (comptime self.pool == null) return DataReaderError.ThreadPoolNotSet;
+            const mut: std.Thread.Mutex = .{};
+            var cur_idx: usize = 0;
+            const wg: std.Thread.WaitGroup = .{};
+            const completed = comptime if (std.meta.hasFn(@TypeOf(writer), "pwrite")) {
+                std.ArrayList(anyerror).init(self.alloc);
+            } else {
+                std.AutoArrayHashMap(usize, anyerror![]u8).init(self.alloc);
+            };
+            defer completed.deinit();
+            for (0..self.numBlocks()) |i| {
+                wg.start();
+                self.pool.?.spawn(
+                    comptime if (std.meta.hasFn(@TypeOf(writer), "pwrite")) {
+                        extractThreadedPWrite;
+                    } else {
+                        extractThreaded;
+                    },
+                    comptime if (std.meta.hasFn(@TypeOf(writer), "pwrite")) {
+                        .{ self, &wg, &completed, i, writer };
+                    } else {
+                        .{ self, &mut, &cur_idx, &wg, &completed, i, writer };
+                    },
+                );
+            }
+            wg.wait();
+            if (completed.items.len > 0) {
+                return completed.items.get(0);
+            }
+            return self.file_size;
+        }
+        fn extractThreaded(
+            self: Self,
+            mut: *std.Thread.Mutex,
+            cur_idx: *usize,
+            wg: *std.Thread.WaitGroup,
+            completed: *std.AutoArrayHashMap(usize, anyerror![]u8),
+            idx: usize,
+            writer: anytype,
+        ) void {
+            if (cur_idx.* >= self.sizes.len + 1) return;
+            defer wg.finish();
+            const block = self.blockAt(idx) catch |err| {
+                cur_idx.* = self.sizes.len + 1;
+                completed.put(idx, err) catch {};
+                return;
+            };
+            defer if (idx < self.sizes.len) {
+                self.alloc.free(block);
+            };
+            mut.lock();
+            defer mut.unlock();
+            if (cur_idx.* == idx) {
+                _ = writer.write(block) catch |err| {
+                    cur_idx.* = self.sizes.len + 1;
+                    completed.put(idx, err) catch {};
+                    return;
+                };
+            } else {
+                completed.put(idx, block) catch |err| {
+                    cur_idx.* = self.sizes.len + 1;
+                    completed.put(idx, err) catch {};
+                    return;
+                };
+            }
+            if (completed.count() == 0) return;
+            for (cur_idx.*..self.numBlocks()) |i| {
+                const val = completed.get(i);
+                if (val == null) return;
+                _ = writer.write(block) catch |err| {
+                    cur_idx.* = self.sizes.len + 1;
+                    completed.put(i, err) catch {};
+                    return;
+                };
+                cur_idx.* += 1;
+                if (completed.count() == 0) return;
+            }
+        }
+        fn extractThreadedPWrite(
+            self: Self,
+            wg: *std.Thread.WaitGroup,
+            completed: *std.ArrayList(anyerror),
+            idx: usize,
+            writer: anytype,
+        ) void {
+            if (completed.items.len > 0) return;
+            defer wg.finish();
+            const block = self.blockAt(idx) catch |err| {
+                completed.append(err) catch {};
+                return;
+            };
+            defer if (idx < self.sizes.len) {
+                self.alloc.free(block);
+            };
+            _ = writer.pwrite(idx * self.block_size, block) catch |err| {
+                completed.append(err) catch {};
+                return;
+            };
+        }
     };
 }