From a121fb7d8ffbd8bed00ed13f746cfa800c74c066 Mon Sep 17 00:00:00 2001
From: SCG82 <scg082+github@gmail.com>
Date: Tue, 7 Jan 2020 07:12:15 -0800
Subject: [PATCH] parallelize using libdispatch (Grand Central Dispatch)

---
 CMakeLists.txt        |  1 +
 src/Dependency.h      |  2 --
 src/DylibBundler.cpp  |  9 +++++----
 src/ParallelForEach.h | 23 +++++++++++++++++++++++
 4 files changed, 29 insertions(+), 6 deletions(-)
 create mode 100644 src/ParallelForEach.h

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4460b7e..3cf07a1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -24,4 +24,5 @@ add_executable(dylibbundler
     src/Settings.h
     src/Utils.cpp
     src/Utils.h
+    src/ParallelForEach.h
 )
diff --git a/src/Dependency.h b/src/Dependency.h
index 1954cae..fb5a165 100644
--- a/src/Dependency.h
+++ b/src/Dependency.h
@@ -6,8 +6,6 @@
 #include <string>
 #include <vector>
 
-//#include "DylibBundler.h"
-
 class DylibBundler;
 
 class Dependency {
diff --git a/src/DylibBundler.cpp b/src/DylibBundler.cpp
index 94b41a7..850201c 100644
--- a/src/DylibBundler.cpp
+++ b/src/DylibBundler.cpp
@@ -12,6 +12,7 @@
 #include <linux/limits.h>
 #endif
 
+#include "ParallelForEach.h"
 #include "Dependency.h"
 #include "Utils.h"
 
@@ -161,18 +162,18 @@ void DylibBundler::bundleDependencies()
     // copy & fix up dependencies
     if (bundleLibs()) {
         createDestDir();
-        for (const auto& dep : deps) {
+        parallel_for_each(deps.begin(), deps.end(), [&](Dependency* dep) {
             dep->CopyToBundle();
             changeLibPathsOnFile(dep->InstallPath());
             fixRpathsOnFile(dep->OriginalPath(), dep->InstallPath());
-        }
+        });
     }
     // fix up input files
     const auto files = filesToFix();
-    for (const auto& file : files) {
+    parallel_for_each(files.begin(), files.end(), [&](const std::string& file) {
         changeLibPathsOnFile(file);
         fixRpathsOnFile(file, file);
-    }
+    });
 }
 
 void DylibBundler::bundleQtPlugins()
diff --git a/src/ParallelForEach.h b/src/ParallelForEach.h
new file mode 100644
index 0000000..5b66f9e
--- /dev/null
+++ b/src/ParallelForEach.h
@@ -0,0 +1,23 @@
+#ifndef DYLIBBUNDLER_PARALLELFOREACH_H
+#define DYLIBBUNDLER_PARALLELFOREACH_H
+
+#include <iterator>
+#include <dispatch/dispatch.h>
+
+template<typename It, typename F>
+inline void parallel_for_each(It a, It b, F&& f)
+{
+    size_t count = std::distance(a,b);
+    using data_t = std::pair<It, F>;
+    data_t helper = data_t(a, std::forward<F>(f));
+    dispatch_apply_f(count,
+                     dispatch_get_global_queue(QOS_CLASS_USER_INTERACTIVE, 0),
+                     &helper,
+                     [](void* ctx, size_t cnt) {
+                         auto* d = static_cast<data_t*>(ctx);
+                         auto elem_it = std::next(d->first, cnt);
+                         (*d).second(*(elem_it));
+                     });
+}
+
+#endif //DYLIBBUNDLER_PARALLELFOREACH_H