Improve passing of arguments to workers

The executor system was built around passing only a single
argument to workers, which was
always PageContext. For other tasks, all actual arguments were packed in
a tuple, which meant we needed intermediate functions to unpack the
tuple.

The situation is now rationlized and resembles how Python handles
argument passing to familiar multiprocessing tools.

src/ocrmypdf/_concurrent.py

@@ -133,5 +133,5 @@ class SerialExecutor(Executor):
     ):  # pylint: disable=unused-argument
         with self.pbar_class(**progress_kwargs) as pbar:
             for args in task_arguments:
-                result = task(args)
+                result = task(*args)
                 task_finished(result, pbar)

src/ocrmypdf/_exec/jbig2enc.py

@@ -25,7 +25,7 @@ def available():
     return True
 
 
-def convert_group(*, cwd, infiles, out_prefix, threshold):
+def convert_group(cwd, infiles, out_prefix, threshold):
     args = [
         'jbig2',
         '-b',
@@ -43,21 +43,9 @@ def convert_group(*, cwd, infiles, out_prefix, threshold):
     return proc
 
 
-def convert_group_mp(args):
-    return convert_group(
-        cwd=args[0], infiles=args[1], out_prefix=args[2], threshold=args[3]
-    )
-
-
-def convert_single(*, cwd, infile, outfile, threshold):
+def convert_single(cwd, infile, outfile, threshold):
     args = ['jbig2', '--pdf', '-t', str(threshold), infile]
     with open(outfile, 'wb') as fstdout:
         proc = run(args, cwd=cwd, stdout=fstdout, stderr=PIPE)
     proc.check_returncode()
     return proc
-
-
-def convert_single_mp(args):
-    return convert_single(
-        cwd=args[0], infile=args[1], outfile=args[2], threshold=args[3]
-    )

src/ocrmypdf/_exec/pngquant.py

@@ -50,7 +50,3 @@ def quantize(input_file: Path, output_file: Path, quality_min: int, quality_max:
     if result.returncode == 0:
         # input_file could be the same as output_file, so we defer the write
         output_file.write_bytes(result.stdout)
-
-
-def quantize_mp(args):
-    return quantize(*args)

src/ocrmypdf/_jobcontext.py

@@ -53,6 +53,12 @@ class PdfContext:
         for n in range(npages):
             yield PageContext(self, n)
 
+    def get_page_context_args(self) -> Iterator[tuple[PageContext]]:
+        """Get all ``PageContext`` for this PDF packaged in tuple for args-splatting."""
+        npages = len(self.pdfinfo)
+        for n in range(npages):
+            yield (PageContext(self, n),)
+
 
 class PageContext:
     """Holds our context for a page.

src/ocrmypdf/_pipelines/hocr_to_ocr_pdf.py

@@ -87,7 +87,7 @@ def exec_hocr_to_ocr_pdf(context: PdfContext, executor: Executor) -> Sequence[st
         ),
         worker_initializer=partial(worker_init, PIL.Image.MAX_IMAGE_PIXELS),
         task=exec_hocrtransform_sync,
-        task_arguments=context.get_page_contexts(),
+        task_arguments=context.get_page_context_args(),
         task_finished=graft_page,
     )
 

src/ocrmypdf/_pipelines/ocr.py

@@ -128,7 +128,7 @@ def exec_concurrent(context: PdfContext, executor: Executor) -> Sequence[str]:
         ),
         worker_initializer=partial(worker_init, PIL.Image.MAX_IMAGE_PIXELS),
         task=exec_page_sync,
-        task_arguments=context.get_page_contexts(),
+        task_arguments=context.get_page_context_args(),
         task_finished=update_page,
     )
 

src/ocrmypdf/_pipelines/pdf_to_hocr.py

@@ -39,7 +39,6 @@ from ocrmypdf._validation import (
 log = logging.getLogger(__name__)
 
 
-
 def exec_page_hocr_sync(page_context: PageContext) -> HOCRResult:
     """Execute a pipeline for a single page hOCR."""
     set_thread_pageno(page_context.pageno + 1)
@@ -82,7 +81,7 @@ def exec_pdf_to_hocr(context: PdfContext, executor: Executor) -> None:
         ),
         worker_initializer=partial(worker_init, PIL.Image.MAX_IMAGE_PIXELS),
         task=exec_page_hocr_sync,
-        task_arguments=context.get_page_contexts(),
+        task_arguments=context.get_page_context_args(),
     )
 
 

src/ocrmypdf/builtin_plugins/concurrency.py

@@ -134,7 +134,7 @@ class StandardExecutor(Executor):
             initializer=initializer,
             initargs=(log_queue, worker_initializer, logging.getLogger("").level),
         ) as executor:
-            futures = [executor.submit(task, args) for args in task_arguments]
+            futures = [executor.submit(task, *args) for args in task_arguments]
             try:
                 for future in as_completed(futures):
                     result = future.result()

src/ocrmypdf/extra_plugins/semfree.py

@@ -94,7 +94,7 @@ def process_loop(
 
     for args in task_args:
         try:
-            result = task(args)
+            result = task(*args)
         except Exception as e:  # pylint: disable=broad-except
             conn.send((MessageType.exception, e))
             break
@@ -123,7 +123,7 @@ class LambdaExecutor(Executor):
         if use_threads and max_workers == 1:
             with self.pbar_class(**progress_kwargs) as pbar:
                 for args in task_arguments:
-                    result = task(args)
+                    result = task(*args)
                     task_finished(result, pbar)
             return
 

src/ocrmypdf/optimize.py

@@ -390,10 +390,10 @@ def _produce_jbig2_images(
 
     if options.jbig2_page_group_size > 1:
         jbig2_args = jbig2_group_args
-        jbig2_convert = jbig2enc.convert_group_mp
+        jbig2_convert = jbig2enc.convert_group
     else:
         jbig2_args = jbig2_single_args
-        jbig2_convert = jbig2enc.convert_single_mp
+        jbig2_convert = jbig2enc.convert_single
 
     executor(
         use_threads=True,
@@ -454,9 +454,9 @@ def convert_to_jbig2(
             )
 
 
-def _optimize_jpeg(args: tuple[Xref, Path, Path, int]) -> tuple[Xref, Path | None]:
-    xref, in_jpg, opt_jpg, jpeg_quality = args
-
+def _optimize_jpeg(
+    xref: Xref, in_jpg: Path, opt_jpg: Path, jpeg_quality: int
+) -> tuple[Xref, Path | None]:
     with Image.open(in_jpg) as im:
         im.save(opt_jpg, optimize=True, quality=jpeg_quality)
 
@@ -515,8 +515,9 @@ def _find_deflatable_jpeg(
     return None
 
 
-def _deflate_jpeg(args: tuple[Pdf, threading.Lock, Xref, int]) -> tuple[Xref, bytes]:
-    pdf, lock, xref, complevel = args
+def _deflate_jpeg(
+    pdf: Pdf, lock: threading.Lock, xref: Xref, complevel: int
+) -> tuple[Xref, bytes]:
     with lock:
         xobj = pdf.get_object(xref, 0)
         try:
@@ -651,7 +652,7 @@ def transcode_pngs(
                 unit='image',
                 disable=not options.progress_bar,
             ),
-            task=pngquant.quantize_mp,
+            task=pngquant.quantize,
             task_arguments=pngquant_args(),
         )
 

src/ocrmypdf/pdfinfo/info.py

@@ -694,8 +694,7 @@ def _pdf_pageinfo_sync_init(pdf: Pdf, infile: Path, pdfminer_loglevel):
         atexit.register(on_process_close)
 
 
-def _pdf_pageinfo_sync(args):
-    pageno, thread_pdf, infile, check_pages, detailed_analysis = args
+def _pdf_pageinfo_sync(pageno, thread_pdf, infile, check_pages, detailed_analysis):
     pdf = thread_pdf if thread_pdf is not None else worker_pdf
     with ExitStack() as stack:
         if not pdf:  # When called with SerialExecutor