新增PDF生成并发设置

backend/app/services/logs.py

@@ -23,6 +23,7 @@ ACTION_LABELS = {
     "export_certificates": "\u5bfc\u51fa\u8bc1\u4e66",
     "create_database_backup": "\u521b\u5efa\u6570\u636e\u5e93\u5907\u4efd",
     "restore_database_backup": "\u56de\u6eda\u6570\u636e\u5e93\u5907\u4efd",
+    "update_pdf_settings": "\u4fee\u6539PDF\u751f\u6210\u8bbe\u7f6e",
     "public_search_certificate": "\u516c\u5f00\u67e5\u8be2\u8bc1\u4e66",
     "public_download_certificate": "\u516c\u5f00\u4e0b\u8f7d\u8bc1\u4e66",
 }
@@ -33,6 +34,7 @@ OBJECT_LABELS = {
     "certificate": "\u8bc1\u4e66",
     "import_batch": "\u5bfc\u5165\u6279\u6b21",
     "database_backup": "\u6570\u636e\u5e93\u5907\u4efd",
+    "system_setting": "\u7cfb\u7edf\u8bbe\u7f6e",
     "public_access": "\u516c\u5f00\u8bbf\u95ee",
 }
 HIGH_RISK_ACTIONS = {
@@ -48,6 +50,7 @@ MEDIUM_RISK_ACTIONS = {
     "confirm_import_batch",
     "create_certificate",
     "create_database_backup",
+    "update_pdf_settings",
 }
 
 
@@ -116,6 +119,8 @@ def log_summary(action: str, object_type: str, object_id: object, detail: dict[s
         filename = detail.get("filename") or object_id
         size_label = detail.get("size_label")
         return f"{label}\uff1a{filename}" + (f"\uff08{size_label}\uff09" if size_label else "")
+    if action == "update_pdf_settings":
+        return f"{label}\uff1a\u5e76\u53d1\u6570 {detail.get('before')} -> {detail.get('after')}"
     if action == "public_search_certificate":
         mode = "\u8bc1\u4e66\u7f16\u53f7" if detail.get("mode") == "certificate_no" else "\u624b\u673a\u53f7"
         return f"{label}\uff1a{detail.get('name') or '-'} \u7528{mode}\u67e5\u8be2\uff0c\u5339\u914d {detail.get('matched_count', 0)} \u6761"

backend/app/services/pdf.py

@@ -1,5 +1,7 @@
+import threading
 from datetime import date, datetime, timedelta
 from pathlib import Path
+from time import monotonic
 
 from PIL import Image, ImageDraw, ImageFont
 
@@ -10,6 +12,35 @@ from app.models import Certificate, CertificateAccessToken, Learner, ProjectCour
 DESIGN_WIDTH = 1024
 DESIGN_HEIGHT = 759
 PDF_BASE_RESOLUTION = 150.0
+PDF_GENERATION_WAIT_TIMEOUT_SECONDS = 120
+
+
+class PdfGenerationBusy(RuntimeError):
+    pass
+
+
+class PdfGenerationLimiter:
+    def __init__(self) -> None:
+        self._condition = threading.Condition()
+        self._active = 0
+
+    def acquire(self, limit: int, timeout_seconds: int = PDF_GENERATION_WAIT_TIMEOUT_SECONDS) -> None:
+        deadline = monotonic() + timeout_seconds
+        with self._condition:
+            while self._active >= limit:
+                remaining = deadline - monotonic()
+                if remaining <= 0:
+                    raise PdfGenerationBusy("当前PDF生成任务较多，请稍后重试")
+                self._condition.wait(remaining)
+            self._active += 1
+
+    def release(self) -> None:
+        with self._condition:
+            self._active = max(0, self._active - 1)
+            self._condition.notify_all()
+
+
+pdf_generation_limiter = PdfGenerationLimiter()
 
 
 def pdf_cache_path(certificate_no: str) -> Path:
@@ -51,6 +82,7 @@ def render_certificate_pdf(
     learner: Learner,
     project: ProjectCourse | None,
     token: CertificateAccessToken,
+    concurrency_limit: int = 2,
 ) -> Path:
     output_path = pdf_cache_path(certificate.certificate_no)
     template_path = certificate_template_path()
@@ -60,8 +92,15 @@ def render_certificate_pdf(
         update_pdf_access_time(certificate)
         return output_path
 
-    image = render_certificate_image(certificate, learner, project)
-    image.save(output_path, "PDF", resolution=pdf_resolution(image))
+    pdf_generation_limiter.acquire(max(1, concurrency_limit))
+    try:
+        if cached_pdf_is_fresh(output_path) and output_path.stat().st_mtime >= latest_renderer_mtime:
+            update_pdf_access_time(certificate)
+            return output_path
+        image = render_certificate_image(certificate, learner, project)
+        image.save(output_path, "PDF", resolution=pdf_resolution(image))
+    finally:
+        pdf_generation_limiter.release()
 
     certificate.pdf_status = "generated"
     certificate.pdf_file_path = str(output_path)

backend/app/services/system_settings.py

@@ -0,0 +1,64 @@
+from datetime import datetime
+
+from sqlalchemy.orm import Session
+
+from app.models import SystemSetting
+
+PDF_GENERATION_CONCURRENCY_KEY = "pdf_generation_concurrency_limit"
+DEFAULT_PDF_GENERATION_CONCURRENCY = 2
+MIN_PDF_GENERATION_CONCURRENCY = 1
+MAX_PDF_GENERATION_CONCURRENCY = 10
+
+
+def ensure_default_settings(db: Session) -> None:
+    if not db.get(SystemSetting, PDF_GENERATION_CONCURRENCY_KEY):
+        db.add(
+            SystemSetting(
+                key=PDF_GENERATION_CONCURRENCY_KEY,
+                value=str(DEFAULT_PDF_GENERATION_CONCURRENCY),
+                description="PDF证书同时生成数量限制",
+            )
+        )
+
+
+def get_pdf_generation_concurrency_limit(db: Session) -> int:
+    setting = db.get(SystemSetting, PDF_GENERATION_CONCURRENCY_KEY)
+    return _coerce_limit(setting.value if setting else None)
+
+
+def get_pdf_settings(db: Session) -> dict[str, object]:
+    ensure_default_settings(db)
+    setting = db.get(SystemSetting, PDF_GENERATION_CONCURRENCY_KEY)
+    return {
+        "pdf_generation_concurrency_limit": get_pdf_generation_concurrency_limit(db),
+        "updated_at": setting.updated_at if setting else None,
+    }
+
+
+def update_pdf_generation_concurrency_limit(db: Session, value: int) -> dict[str, object]:
+    limit = _coerce_limit(value)
+    ensure_default_settings(db)
+    setting = db.get(SystemSetting, PDF_GENERATION_CONCURRENCY_KEY)
+    if setting is None:
+        setting = SystemSetting(
+            key=PDF_GENERATION_CONCURRENCY_KEY,
+            value=str(limit),
+            description="PDF证书同时生成数量限制",
+        )
+        db.add(setting)
+    else:
+        setting.value = str(limit)
+        setting.updated_at = datetime.utcnow()
+    db.flush()
+    return {
+        "pdf_generation_concurrency_limit": limit,
+        "updated_at": setting.updated_at,
+    }
+
+
+def _coerce_limit(value: object) -> int:
+    try:
+        limit = int(value)
+    except (TypeError, ValueError):
+        limit = DEFAULT_PDF_GENERATION_CONCURRENCY
+    return max(MIN_PDF_GENERATION_CONCURRENCY, min(MAX_PDF_GENERATION_CONCURRENCY, limit))