refactor(cmd): improve file handling and reduce allocations

- Use openFile instead of access for genesis file existence check
- Replace allocPrint with bufPrint for genesis URL to avoid allocation
- Use makeOpenPath to simplify directory creation logic
- Remove unnecessary min cap on decompression buffer size
- Add TODO for future path allocation improvements

Author: yewman

src/cmd.zig

@@ -1341,10 +1341,19 @@ fn ensureGenesis(
         &.{ cfg.validator_dir, "genesis.bin" },
     );
     errdefer allocator.free(existing_path);
-    if (!std.meta.isError(std.fs.cwd().access(existing_path, .{}))) {
+    const maybe_genesis_file: ?std.fs.File = std.fs.cwd().openFile(
+        existing_path,
+        .{},
+    ) catch |err| switch (err) {
+        error.FileNotFound => null,
+        else => return err,
+    };
+    if (maybe_genesis_file != null) {
         logger.info().logf("Using existing genesis file: {s}", .{existing_path});
+        maybe_genesis_file.?.close();
         return existing_path;
     }
+    allocator.free(existing_path);
 
     // Determine cluster for genesis
     const cluster = try cfg.gossip.getCluster() orelse {

src/config.zig

@@ -43,15 +43,21 @@ pub const Cmd = struct {
             .localnet => return error.MustProvideGenesisFileForLocalHost,
         } else return null;
 
-        std.fs.cwd().access(local_path, .{ .read = true }) catch {
+        const genesis_file = std.fs.cwd().openFile(local_path, .{}) catch {
             return null;
         };
+        genesis_file.close();
+
+        return local_path;
     }
 
     /// Derives a path relative to validator_dir if the param equals the default value.
     /// This is used to allow paths like snapshot_dir and geyser.pipe_path to be relative
     /// to validator_dir when using their default values, while still allowing explicit
     /// overrides.
+    /// TODO:
+    ///     - remove alloc by using fixed-size buffers for paths
+    ///     - https://github.com/orgs/Syndica/projects/2/views/10?pane=issue&itemId=156092227)
     pub fn derivePathFromValidatorDir(
         self: Cmd,
         allocator: std.mem.Allocator,

src/core/genesis_download.zig

@@ -36,12 +36,12 @@ pub fn downloadAndExtractGenesis(
     output_dir: []const u8,
     logger: Logger,
 ) DownloadError![]const u8 {
-    const genesis_url = try std.fmt.allocPrint(
-        allocator,
+    var genesis_url_buf: [std.fs.max_path_bytes]u8 = @splat(0);
+    const genesis_url = try std.fmt.bufPrint(
+        &genesis_url_buf,
         "{s}/{s}",
         .{ cluster_url, DEFAULT_GENESIS_ARCHIVE },
     );
-    defer allocator.free(genesis_url);
 
     logger.info().logf("Downloading genesis from {s}...", .{genesis_url});
     const archive_data = try downloadGenesisArchive(allocator, genesis_url, logger);
@@ -91,7 +91,7 @@ fn downloadGenesisArchive(
 /// Decompresses bz2 data using libbz2
 fn decompressBz2(allocator: Allocator, compressed_data: []const u8) DownloadError![]u8 {
     // Start with an estimate of 10x compression ratio
-    var dest_len: u32 = @intCast(@min(compressed_data.len * 10, 500 * 1024 * 1024));
+    var dest_len: u32 = @intCast(compressed_data.len * 10);
     var decompressed = allocator.alloc(u8, dest_len) catch return error.OutOfMemory;
     errdefer allocator.free(decompressed);
 
@@ -135,13 +135,8 @@ fn extractGenesisFromTar(
     output_dir: []const u8,
     logger: Logger,
 ) DownloadError![]const u8 {
-    std.fs.cwd().makePath(output_dir) catch |err| {
-        logger.err().logf("Failed to create output directory: {}", .{err});
-        return error.TarExtractError;
-    };
-
-    var dir = std.fs.cwd().openDir(output_dir, .{}) catch |err| {
-        logger.err().logf("Failed to open output directory: {}", .{err});
+    var dir = std.fs.cwd().makeOpenPath(output_dir, .{}) catch |err| {
+        logger.err().logf("Failed to open/create output directory: {}", .{err});
         return error.TarExtractError;
     };
     defer dir.close();