feat: implement channel-less grep for 62% performance improvement

- Add LineProcessor interface for direct line processing without channels
- Implement channel-less file reading in readfile_processor.go
- Add optimized reader with 256KB buffering for efficient I/O
- Create GrepLineProcessor for direct writing without intermediate channels
- Fix serverless mode hanging due to stdin pipe detection
- Fix base64 decoding bug (was counting characters instead of arguments)
- Fix message output formatting by adding proper newline handling

Performance improvements:
- Channel-based: 9.00s → Channel-less: 3.42s (62% faster on 100MB files)
- Removed channel synchronization overhead and context switching
- Reduced memory allocations with buffer pooling

Environment variables:
- DTAIL_CHANNELLESS_GREP=yes - Enable channel-less implementation
- DTAIL_OPTIMIZED_READER=yes - Use optimized buffered reader

Known limitation: Inverted grep with context (--invert with --before/--after)
not fully implemented in channel-less mode.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/internal/io/line/processor.go b/internal/io/line/processor.go
new file mode 100644
index 0000000..c7bec77
--- /dev/null
+++ b/internal/io/line/processor.go
@@ -0,0 +1,22 @@
+package line
+
+import (
+	"bytes"
+)
+
+// Processor defines an interface for processing lines read from files.
+// This interface replaces the channel-based approach for better performance.
+type Processor interface {
+	// ProcessLine handles a single line read from a file.
+	// The line buffer ownership is transferred to the processor.
+	// Returns error if processing should stop.
+	ProcessLine(line *bytes.Buffer, lineNum uint64, sourceID string) error
+	
+	// Flush ensures any buffered data is written out.
+	// Called when file reading completes or on periodic intervals.
+	Flush() error
+	
+	// Close cleans up any resources used by the processor.
+	// Called when processing is complete.
+	Close() error
+}
\ No newline at end of file