Async indexing (#10)

* async indexing | small refactoring

* async indexing optional

* performance improvement

* fix security in async index

Author: cigolpl

binding.gyp

@@ -2,15 +2,16 @@
   "targets": [{
     "target_name": "itemsjs_addon",
       "cflags!": [ "-fno-exceptions" ],
-      "cflags_cc!": ["-O3", "-fno-exceptions", "-std=gnu++0x", "-std=gnu++1y"],
-      "cflags_cc+": ["-O3", "-std=c++17"],
+      "cflags_cc!": ["-pthread", "-O3", "-fno-exceptions", "-std=gnu++0x", "-std=gnu++1y"],
+      "cflags_cc+": ["-pthread", "-O3", "-std=c++17"],
       "sources": [
         "cpp/main.cpp",
         "cpp/itemsjs.cpp",
         "cpp/simdjson.cpp"
       ],
       'include_dirs': [
-        "<!@(node -p \"require('node-addon-api').include\")"
+        "<!@(node -p \"require('node-addon-api').include\")",
+        "<!@(node -p \"require('napi-thread-safe-callback').include\")"
       ],
       'libraries': [
         "<!(node -p \"require('./src/binding').liblmdb()\")"
@@ -28,7 +29,7 @@
         "<!(node -p \"require('node-addon-api').gyp\")"
 
       ],
-      'defines': [ 'NAPI_DISABLE_CPP_EXCEPTIONS' ],
+      'defines': [],
 
       'conditions': [
         ['OS=="linux"', {