Get pool size controls working

src/calibre/db/backend.py

@@ -957,7 +957,7 @@ class DB:
     @fts_num_of_workers.setter
     def fts_num_of_workers(self, num):
         if self.fts_enabled:
-            self.fts.num_of_workers = num
+            self.fts.pool.num_of_workers = num
 
     def get_next_fts_job(self):
         return self.fts.get_next_fts_job()

src/calibre/db/cache.py

@@ -456,11 +456,9 @@ class Cache:
         return num_to_scan, (self.backend.get('SELECT COUNT(*) FROM main.data')[0][0] or 0)
 
     @write_api
-    def enable_fts(self, enabled=True, start_pool=True, mark_all_dirty=False):
+    def enable_fts(self, enabled=True, start_pool=True):
         fts = self.backend.enable_fts(weakref.ref(self) if enabled else None)
         if fts and start_pool:  # used in the tests
-            if mark_all_dirty:
-                fts.dirty_existing()
             self.start_fts_pool()
         if not fts and self.fts_queue_thread:
             self.fts_job_queue.put(None)
@@ -534,7 +532,7 @@ class Cache:
     @api
     def set_fts_num_of_workers(self, num=None):
         existing = self.backend.fts_num_of_workers
-        if num is not None and num != existing:
+        if num is not None:
             self.backend.fts_num_of_workers = num
             if num > existing:
                 self.queue_next_fts_job()

src/calibre/db/fts/pool.py

@@ -9,10 +9,11 @@ import sys
 import traceback
 from contextlib import suppress
 from queue import Queue
-from threading import Thread, Event
+from threading import Event, Thread
 from time import monotonic
 
-from calibre import human_readable
+from calibre import detect_ncpus, human_readable
+from calibre.utils.config import dynamic
 from calibre.utils.ipc.simple_worker import start_pipe_worker
 
 check_for_work = object()
@@ -116,8 +117,13 @@ class Worker(Thread):
 
 class Pool:
 
+    MAX_WORKERS_PREF_NAME = 'fts_pool_max_workers'
+
     def __init__(self, dbref):
-        self.max_workers = 1
+        try:
+            self.max_workers = min(max(1, int(dynamic.get(self.MAX_WORKERS_PREF_NAME, 1))), detect_ncpus())
+        except Exception:
+            self.max_workers = 1
         self.jobs_queue = Queue()
         self.supervise_queue = Queue()
         self.workers = []
@@ -142,8 +148,6 @@ class Pool:
     def create_worker(self):
         w = Worker(self.jobs_queue, self.supervise_queue)
         w.start()
-        while not w.is_alive():
-            w.join(0.01)
         return w
 
     def shrink_workers(self):
@@ -162,12 +166,14 @@ class Pool:
     def num_of_workers(self, num):
         self.initialize()
         self.prune_dead_workers()
-        num = max(1, num)
-        self.max_workers = num
-        if num > len(self.workers):
-            self.expand_workers()
-        elif num < self.workers:
-            self.shrink_workers()
+        num = min(max(1, num), detect_ncpus())
+        if num != self.max_workers:
+            self.max_workers = num
+            dynamic.set(self.MAX_WORKERS_PREF_NAME, num)
+            if num > len(self.workers):
+                self.expand_workers()
+            elif num < len(self.workers):
+                self.shrink_workers()
 
     @property
     def num_of_idle_workers(self):

src/calibre/db/tests/fts_api.py

@@ -26,6 +26,9 @@ class FTSAPITest(BaseTest):
     def setUp(self):
         super().setUp()
         from calibre_extensions.sqlite_extension import set_ui_language
+        from calibre.db.fts.pool import Pool
+        self.orig_pw_pref_name = Pool.MAX_WORKERS_PREF_NAME
+        Pool.MAX_WORKERS_PREF_NAME = 'test_fts_max_workers'
         set_ui_language('en')
         self.libraries_to_close = []
 
@@ -33,6 +36,8 @@ class FTSAPITest(BaseTest):
         [c.close() for c in self.libraries_to_close]
         super().tearDown()
         from calibre_extensions.sqlite_extension import set_ui_language
+        from calibre.db.fts.pool import Pool
+        Pool.MAX_WORKERS_PREF_NAME = self.orig_pw_pref_name
         set_ui_language('en')
 
     def new_library(self):

src/calibre/gui2/fts/scan.py

@@ -3,38 +3,117 @@
 # License: GPL v3 Copyright: 2022, Kovid Goyal <kovid at kovidgoyal.net>
 
 import os
-from qt.core import QCheckBox, QLabel, QVBoxLayout, QWidget
+from qt.core import (
+    QCheckBox, QHBoxLayout, QLabel, QSpinBox, QTimer, QVBoxLayout, QWidget
+)
 
+from calibre import detect_ncpus
+from calibre.db.fts.pool import Pool
 from calibre.gui2.dialogs.confirm_delete import confirm
 from calibre.gui2.fts.utils import get_db
+from calibre.utils.config import dynamic
+
+
+class IndexingProgress:
+
+    def __init__(self):
+        self.left = self.total = 0
+
+    @property
+    def complete(self):
+        return not self.left or not self.total
+
+
+class ScanProgress(QWidget):
+
+    def __init__(self, parent):
+        super().__init__(parent)
+        self.l = l = QVBoxLayout(self)
+        l.setContentsMargins(0, 0, 0, 0)
+        self.status_label = la = QLabel('\xa0')
+        la.setWordWrap(True)
+        l.addWidget(la)
+        self.h = h = QHBoxLayout()
+        l.addLayout(h)
+        self.niwl = la = QLabel(_('Number of workers used for indexing:'))
+        h.addWidget(la)
+        self.num_of_workers = n = QSpinBox(self)
+        n.setMinimum(1)
+        n.setMaximum(detect_ncpus())
+        self.debounce_timer = t = QTimer(self)
+        t.setInterval(750)
+        t.timeout.connect(self.change_num_of_workers)
+        t.setSingleShot(True)
+        n.valueChanged.connect(self.schedule_change_num_of_workers)
+        try:
+            c = min(max(1, int(dynamic.get(Pool.MAX_WORKERS_PREF_NAME, 1))), n.maximum())
+        except Exception:
+            c = 1
+        n.setValue(c)
+        h.addWidget(n), h.addStretch(10)
+        self.wl = la = QLabel(_(
+            'Increasing the number of workers used for indexing will'
+            ' speed up indexing at the cost of using more of the computer\'s resources.'
+            ' Changes will take a few seconds to take effect.'
+        ))
+        la.setWordWrap(True)
+        l.addWidget(la)
+
+    def schedule_change_num_of_workers(self):
+        self.debounce_timer.stop()
+        self.debounce_timer.start()
+
+    def change_num_of_workers(self):
+        get_db().set_fts_num_of_workers(self.num_of_workers.value())
+
+    def update(self, indexing_progress):
+        if indexing_progress.complete:
+            t = _('All book files indexed')
+        else:
+            done = indexing_progress.total - indexing_progress.left
+            t = _('{0} of {1} book files ({2:.0%}) have been indexed').format(
+                done, indexing_progress.total, done / indexing_progress.total)
+        self.status_label.setText(t)
 
 
 class ScanStatus(QWidget):
 
     def __init__(self, parent=None):
         super().__init__(parent)
+        self.indexing_progress = IndexingProgress()
         self.l = l = QVBoxLayout(self)
         l.setContentsMargins(0, 0, 0, 0)
 
         self.enable_fts = b = QCheckBox(self)
         b.setText(_('&Index books in this library to allow searching their full text'))
+        b.setChecked(self.db.is_fts_enabled())
         l.addWidget(b)
         self.enable_msg = la = QLabel('<p>' + _(
             'In order to search the full text of books, the text must first be <i>indexed</i>. Once enabled, indexing is done'
             ' automatically, in the background, whenever new books are added to this calibre library.'))
         la.setWordWrap(True)
         l.addWidget(la)
+        self.scan_progress = sc = ScanProgress(self)
+        l.addWidget(sc)
 
         l.addStretch(10)
         self.apply_fts_state()
         self.enable_fts.toggled.connect(self.change_fts_state)
+        self.indexing_status_timer = t = QTimer(self)
+        t.timeout.connect(self.update_stats)
+        t.start(1000)
+        self.update_stats()
+
+    def update_stats(self):
+        self.indexing_progress.left, self.indexing_progress.total = self.db.fts_indexing_progress()
+        self.scan_progress.update(self.indexing_progress)
 
     def change_fts_state(self):
         if not self.enable_fts.isChecked() and not confirm(_(
             'Disabling indexing will mean that all books will have to be re-checked when re-enabling indexing. Are you sure?'
         ), 'disable-fts-indexing', self):
             return
-        self.db.enable_fts(enabled=self.enable_fts.isChecked(), mark_all_dirty=True)
+        self.db.enable_fts(enabled=self.enable_fts.isChecked())
         self.apply_fts_state()
 
     def apply_fts_state(self):
@@ -44,6 +123,7 @@ class ScanStatus(QWidget):
         f.setBold(not indexing_enabled)
         b.setFont(f)
         self.enable_msg.setVisible(not indexing_enabled)
+        self.scan_progress.setVisible(indexing_enabled)
 
     @property
     def db(self):