Orthanc patch: Release large-dicom semaphore-lock directly after reading index

release-large-dicom-lock-early-on-default.patch

# HG changeset patch
# User Tilman Vogel <tilman.vogel@web.de>
# Date 1778599439 -7200
#      Tue May 12 17:23:59 2026 +0200
# Node ID 738952aeb03260dca49be0cb51e05f3bbc0114af
# Parent  fa7123b2930a94a4a3f0411a1af7e16a626f2c65
Release large-dicom semaphore-lock directly after reading index

... and before reading the payload from storage to improve parallelism
for "small" payloads.

diff -r fa7123b2930a -r 738952aeb032 OrthancServer/Sources/ServerContext.cpp
--- a/OrthancServer/Sources/ServerContext.cpp	Tue Jan 27 20:02:51 2026 +0100
+++ b/OrthancServer/Sources/ServerContext.cpp	Tue May 12 17:23:59 2026 +0200
@@ -1375,6 +1375,17 @@
                                 std::string& attachmentId,
                                 const std::string& instancePublicId)
   {
+    std::unique_ptr<Semaphore::Locker> dummyLargeDicomLocker;
+    ReadDicom(dicom, attachmentId, instancePublicId, dummyLargeDicomLocker, 0);
+  }
+
+
+  void ServerContext::ReadDicom(std::string& dicom,
+                                std::string& attachmentId,
+                                const std::string& instancePublicId,
+                                std::unique_ptr<Semaphore::Locker>& largeDicomLocker,
+                                std::size_t largeDicomThreshold)
+  {
     FileInfo attachment;
     int64_t revision;
 
@@ -1388,6 +1399,11 @@
     assert(attachment.GetContentType() == FileContentType_Dicom);
     attachmentId = attachment.GetUuid();
 
+    if (attachment.GetUncompressedSize() < largeDicomThreshold)
+    {
+      largeDicomLocker.reset(NULL);
+    }
+
     ReadAttachment(dicom, attachment, true /* uncompress */);
   }
 
@@ -1399,6 +1415,17 @@
     ReadDicom(dicom, attachmentId, instancePublicId);    
   }
 
+
+  void ServerContext::ReadDicom(std::string& dicom,
+                                const std::string& instancePublicId,
+                                std::unique_ptr<Semaphore::Locker>& largeDicomLocker,
+                                std::size_t largeDicomThreshold)
+  {
+    std::string attachmentId;
+    ReadDicom(dicom, attachmentId, instancePublicId, largeDicomLocker, largeDicomThreshold);
+  }
+
+
   void ServerContext::ReadDicomForHeader(std::string& dicom,
                                          const std::string& instancePublicId)
   {
@@ -1513,16 +1540,11 @@
 
       // Throttle to avoid loading several large DICOM files simultaneously
       largeDicomLocker_.reset(new Semaphore::Locker(context.largeDicomThrottler_));
-      
-      context_.ReadDicom(buffer_, instancePublicId_);
 
       // Release the throttle if loading "small" DICOM files (under
       // 50MB, which is an arbitrary value)
-      if (buffer_.size() < 50 * 1024 * 1024)
-      {
-        largeDicomLocker_.reset(NULL);
-      }
-      
+      context_.ReadDicom(buffer_, instancePublicId_, largeDicomLocker_, 50 * 1024 * 1024);
+
       dicom_.reset(new ParsedDicomFile(buffer_));
       dicomSize_ = buffer_.size();
     }
diff -r fa7123b2930a -r 738952aeb032 OrthancServer/Sources/ServerContext.h
--- a/OrthancServer/Sources/ServerContext.h	Tue Jan 27 20:02:51 2026 +0100
+++ b/OrthancServer/Sources/ServerContext.h	Tue May 12 17:23:59 2026 +0200
@@ -400,9 +400,20 @@
                    const std::string& instancePublicId);
 
     void ReadDicom(std::string& dicom,
+                   const std::string& instancePublicId,
+                   std::unique_ptr<Semaphore::Locker>& largeDicomLocker,
+                   std::size_t largeDicomThreshold);
+
+    void ReadDicom(std::string& dicom,
                    std::string& attachmentId,
                    const std::string& instancePublicId);
 
+    void ReadDicom(std::string& dicom,
+                   std::string& attachmentId,
+                   const std::string& instancePublicId,
+                   std::unique_ptr<Semaphore::Locker>& largeDicomLocker,
+                   std::size_t largeDicomThreshold);
+
     void ReadDicomForHeader(std::string& dicom,
                             const std::string& instancePublicId);