Expose libvips warnings via NODE_DEBUG env var

docs/changelog.md

@@ -1,5 +1,15 @@
 # Changelog
 
+### v0.18 - "*ridge*"
+
+Requires libvips v8.5.2.
+
+#### v0.18.0 - TBD
+
+* Expose warnings from libvips via NODE_DEBUG=sharp environment variable.
+  [#607](https://github.com/lovell/sharp/issues/607)
+  [@puzrin](https://github.com/puzrin)
+
 ### v0.17 - "*quill*"
 
 Requires libvips v8.4.2.

lib/constructor.js

@@ -24,6 +24,9 @@ let versions = {
   } catch (err) {}
 })();
 
+// Use NODE_DEBUG=sharp to enable libvips warnings
+const debuglog = util.debuglog('sharp');
+
 /**
  * @class Sharp
  *
@@ -174,6 +177,8 @@ const Sharp = function (input, options) {
     tiffSquash: false,
     tileSize: 256,
     tileOverlap: 0,
+    // Function to notify of libvips warnings
+    debuglog: debuglog,
     // Function to notify of queue length changes
     queueListener: function (queueLength) {
       queue.emit('change', queueLength);

package.json

@@ -99,6 +99,7 @@
   "cc": {
     "linelength": "120",
     "filter": [
+      "build/c++11",
       "build/include",
       "runtime/indentation_namespace"
     ]

src/common.cc

@@ -16,6 +16,8 @@
 #include <string>
 #include <string.h>
 #include <vector>
+#include <queue>
+#include <mutex>
 
 #include <node.h>
 #include <node_buffer.h>
@@ -354,6 +356,33 @@ namespace sharp {
     }
   }
 
+  /*
+    Temporary buffer of warnings
+  */
+  std::queue<std::string> vipsWarnings;
+  std::mutex vipsWarningsMutex;
+
+  /*
+    Called with warnings from the glib-registered "VIPS" domain
+  */
+  void VipsWarningCallback(char const* log_domain, GLogLevelFlags log_level, char const* message, void* ignore) {
+    std::lock_guard<std::mutex> lock(vipsWarningsMutex);
+    vipsWarnings.emplace(message);
+  }
+
+  /*
+    Pop the oldest warning message from the queue
+  */
+  std::string VipsWarningPop() {
+    std::string warning;
+    std::lock_guard<std::mutex> lock(vipsWarningsMutex);
+    if (!vipsWarnings.empty()) {
+      warning = vipsWarnings.front();
+      vipsWarnings.pop();
+    }
+    return warning;
+  }
+
   /*
     Calculate the (left, top) coordinates of the output image
     within the input image, applying the given gravity.

src/common.h

@@ -189,6 +189,16 @@ namespace sharp {
   */
   void FreeCallback(char* data, void* hint);
 
+  /*
+    Called with warnings from the glib-registered "VIPS" domain
+  */
+  void VipsWarningCallback(char const* log_domain, GLogLevelFlags log_level, char const* message, void* ignore);
+
+  /*
+    Pop the oldest warning message from the queue
+  */
+  std::string VipsWarningPop();
+
   /*
     Calculate the (left, top) coordinates of the output image
     within the input image, applying the given gravity.

src/metadata.cc

@@ -25,9 +25,10 @@
 class MetadataWorker : public Nan::AsyncWorker {
  public:
   MetadataWorker(
-    Nan::Callback *callback, MetadataBaton *baton,
-    std::vector<v8::Local<v8::Object>> const buffersToPersist)
-    : Nan::AsyncWorker(callback), baton(baton), buffersToPersist(buffersToPersist) {
+    Nan::Callback *callback, MetadataBaton *baton, Nan::Callback *debuglog,
+    std::vector<v8::Local<v8::Object>> const buffersToPersist) :
+    Nan::AsyncWorker(callback), baton(baton), debuglog(debuglog),
+    buffersToPersist(buffersToPersist) {
     // Protect Buffer objects from GC, keyed on index
     std::accumulate(buffersToPersist.begin(), buffersToPersist.end(), 0,
       [this](uint32_t index, v8::Local<v8::Object> const buffer) -> uint32_t {
@@ -132,12 +133,21 @@ class MetadataWorker : public Nan::AsyncWorker {
     delete baton->input;
     delete baton;
 
+    // Handle warnings
+    std::string warning = sharp::VipsWarningPop();
+    while (!warning.empty()) {
+      v8::Local<v8::Value> message[1] = { New(warning).ToLocalChecked() };
+      debuglog->Call(1, message);
+      warning = sharp::VipsWarningPop();
+    }
+
     // Return to JavaScript
     callback->Call(2, argv);
   }
 
  private:
   MetadataBaton* baton;
+  Nan::Callback *debuglog;
   std::vector<v8::Local<v8::Object>> buffersToPersist;
 };
 
@@ -155,9 +165,12 @@ NAN_METHOD(metadata) {
   // Input
   baton->input = sharp::CreateInputDescriptor(sharp::AttrAs<v8::Object>(options, "input"), buffersToPersist);
 
+  // Function to notify of libvips warnings
+  Nan::Callback *debuglog = new Nan::Callback(sharp::AttrAs<v8::Function>(options, "debuglog"));
+
   // Join queue for worker thread
   Nan::Callback *callback = new Nan::Callback(info[1].As<v8::Function>());
-  Nan::AsyncQueueWorker(new MetadataWorker(callback, baton, buffersToPersist));
+  Nan::AsyncQueueWorker(new MetadataWorker(callback, baton, debuglog, buffersToPersist));
 
   // Increment queued task counter
   g_atomic_int_inc(&sharp::counterQueue);

src/pipeline.cc

@@ -33,9 +33,10 @@
 class PipelineWorker : public Nan::AsyncWorker {
  public:
   PipelineWorker(
-    Nan::Callback *callback, PipelineBaton *baton, Nan::Callback *queueListener,
-    std::vector<v8::Local<v8::Object>> const buffersToPersist)
-    : Nan::AsyncWorker(callback), baton(baton), queueListener(queueListener), buffersToPersist(buffersToPersist) {
+    Nan::Callback *callback, PipelineBaton *baton, Nan::Callback *debuglog, Nan::Callback *queueListener,
+    std::vector<v8::Local<v8::Object>> const buffersToPersist) :
+    Nan::AsyncWorker(callback), baton(baton), debuglog(debuglog), queueListener(queueListener),
+    buffersToPersist(buffersToPersist) {
     // Protect Buffer objects from GC, keyed on index
     std::accumulate(buffersToPersist.begin(), buffersToPersist.end(), 0,
       [this](uint32_t index, v8::Local<v8::Object> const buffer) -> uint32_t {
@@ -979,6 +980,14 @@ class PipelineWorker : public Nan::AsyncWorker {
       });
     delete baton;
 
+    // Handle warnings
+    std::string warning = sharp::VipsWarningPop();
+    while (!warning.empty()) {
+      v8::Local<v8::Value> message[1] = { New(warning).ToLocalChecked() };
+      debuglog->Call(1, message);
+      warning = sharp::VipsWarningPop();
+    }
+
     // Decrement processing task counter
     g_atomic_int_dec_and_test(&sharp::counterProcess);
     v8::Local<v8::Value> queueLength[1] = { New<v8::Uint32>(sharp::counterQueue) };
@@ -991,6 +1000,7 @@ class PipelineWorker : public Nan::AsyncWorker {
 
  private:
   PipelineBaton *baton;
+  Nan::Callback *debuglog;
   Nan::Callback *queueListener;
   std::vector<v8::Local<v8::Object>> buffersToPersist;
 
@@ -1239,12 +1249,15 @@ NAN_METHOD(pipeline) {
     baton->accessMethod = VIPS_ACCESS_RANDOM;
   }
 
+  // Function to notify of libvips warnings
+  Nan::Callback *debuglog = new Nan::Callback(AttrAs<v8::Function>(options, "debuglog"));
+
   // Function to notify of queue length changes
   Nan::Callback *queueListener = new Nan::Callback(AttrAs<v8::Function>(options, "queueListener"));
 
   // Join queue for worker thread
   Nan::Callback *callback = new Nan::Callback(info[1].As<v8::Function>());
-  Nan::AsyncQueueWorker(new PipelineWorker(callback, baton, queueListener, buffersToPersist));
+  Nan::AsyncQueueWorker(new PipelineWorker(callback, baton, debuglog, queueListener, buffersToPersist));
 
   // Increment queued task counter
   g_atomic_int_inc(&sharp::counterQueue);

src/sharp.cc

@@ -24,6 +24,9 @@
 NAN_MODULE_INIT(init) {
   vips_init("sharp");
 
+  g_log_set_handler("VIPS", static_cast<GLogLevelFlags>(G_LOG_LEVEL_WARNING),
+    static_cast<GLogFunc>(sharp::VipsWarningCallback), nullptr);
+
   // Methods available to JavaScript
   Nan::Set(target, Nan::New("metadata").ToLocalChecked(),
     Nan::GetFunction(Nan::New<v8::FunctionTemplate>(metadata)).ToLocalChecked());