Enable the C wrapper to extract model to memory and initialize model from memory

vowpalwabbit/parser.cc

@@ -1016,6 +1016,10 @@ const char* get_tag(example* ec)
 size_t get_feature_number(example* ec)
 { return ec->num_features;
 }
+
+float get_confidence(example* ec)
+{ return ec->confidence;
+}
 }
 
 void initialize_examples(vw& all)

vowpalwabbit/vw.h

@@ -87,6 +87,7 @@ uint32_t* get_multilabel_predictions(example* ec, size_t& len);
 size_t get_tag_length(example* ec);
 const char* get_tag(example* ec);
 size_t get_feature_number(example* ec);
+float get_confidence(example* ec);
 feature* get_features(vw& all, example* ec, size_t& feature_number);
 void return_features(feature* f);
 

vowpalwabbit/vwdll.cpp

@@ -144,6 +144,10 @@ VW_DLL_MEMBER size_t VW_CALLING_CONV VW_GetFeatureNumber(VW_EXAMPLE e)
 { return VW::get_feature_number(static_cast<example*>(e));
 }
 
+VW_DLL_MEMBER float VW_CALLING_CONV VW_GetConfidence(VW_EXAMPLE e)
+{ return VW::get_confidence(static_cast<example*>(e));
+}
+
 VW_DLL_MEMBER VW_FEATURE VW_CALLING_CONV VW_GetFeatures(VW_HANDLE handle, VW_EXAMPLE e, size_t* plen)
 { vw* pointer = static_cast<vw*>(handle);
   return VW::get_features(*pointer, static_cast<example*>(e), *plen);
@@ -274,4 +278,64 @@ VW_DLL_MEMBER void VW_CALLING_CONV VW_SaveModel(VW_HANDLE handle)
 
   return VW::save_predictor(*pointer, name);
 }
+
+
+class memory_io_buf : public io_buf
+{
+public:
+    memory_io_buf() : readOffset(0) {
+        files.push_back(-1); // this is a hack because buf will do nothing if files is empty
+    }
+
+    virtual ssize_t write_file(int file, const void* buf, size_t nbytes) {
+        auto byteBuf = reinterpret_cast<const char*>(buf);
+        data.insert(data.end(), &byteBuf[0], &byteBuf[nbytes]);
+        return nbytes;
+    }
+
+    virtual ssize_t read_file(int f, void* buf, size_t nbytes) {
+        nbytes = min(nbytes, data.size()-readOffset);
+        copy(data.data()+readOffset, data.data()+readOffset+nbytes, reinterpret_cast<char *>(buf));
+        readOffset += nbytes;
+        return nbytes;
+    }
+
+    char* GetDataPointer() {
+        return data.data();
+    }
+
+    size_t GetDataSize() const {
+        return data.size();
+    }
+
+private:
+    vector<char> data;
+    size_t readOffset;
+};
+
+VW_DLL_MEMBER VW_HANDLE VW_CALLING_CONV VW_InitializeWithModel(const char * pstrArgs, const char * modelData, size_t modelDataSize)
+{
+    unique_ptr<memory_io_buf> buf(new memory_io_buf);
+    buf->write_file(-1, modelData, modelDataSize);
+
+    vw* all = VW::initialize(string(pstrArgs), buf.get());
+    return static_cast<VW_HANDLE>(all);
+}
+
+VW_DLL_MEMBER void VW_CALLING_CONV VW_CopyModelData(VW_HANDLE handle, VW_IOBUF* outputBufferHandle, char** outputData, size_t* outputSize) {
+    vw* pointer = static_cast<vw*>(handle);
+
+    memory_io_buf* buf = new(memory_io_buf);
+    VW::save_predictor(*pointer, *buf);
+
+    *outputBufferHandle = buf;
+    *outputSize = buf->GetDataSize();
+    *outputData = buf->GetDataPointer();
+}
+
+VW_DLL_MEMBER void VW_CALLING_CONV VW_FreeIOBuf(VW_IOBUF bufferHandle) {
+    delete static_cast<memory_io_buf*>(bufferHandle);
 }
+
+}
+

vowpalwabbit/vwdll.h

@@ -57,6 +57,7 @@ typedef void * VW_EXAMPLE;
 typedef void * VW_LABEL;
 typedef void * VW_FEATURE_SPACE;
 typedef void * VW_FEATURE;
+typedef void * VW_IOBUF;
 
 const VW_HANDLE INVALID_VW_HANDLE = VW_TYPE_SAFE_NULL;
 const VW_HANDLE INVALID_VW_EXAMPLE = VW_TYPE_SAFE_NULL;
@@ -65,6 +66,7 @@ const VW_HANDLE INVALID_VW_EXAMPLE = VW_TYPE_SAFE_NULL;
 VW_DLL_MEMBER VW_HANDLE VW_CALLING_CONV VW_Initialize(const char16_t * pstrArgs);
 #endif
 VW_DLL_MEMBER VW_HANDLE VW_CALLING_CONV VW_InitializeA(const char * pstrArgs);
+VW_DLL_MEMBER VW_HANDLE VW_CALLING_CONV VW_InitializeWithModel(const char * pstrArgs, const char * modelData, size_t modelDataSize);
 
 VW_DLL_MEMBER void VW_CALLING_CONV VW_Finish_Passes(VW_HANDLE handle);
 VW_DLL_MEMBER void VW_CALLING_CONV VW_Finish(VW_HANDLE handle);
@@ -93,6 +95,7 @@ VW_DLL_MEMBER float VW_CALLING_CONV VW_GetTopicPrediction(VW_EXAMPLE e, size_t i
 VW_DLL_MEMBER size_t VW_CALLING_CONV VW_GetTagLength(VW_EXAMPLE e);
 VW_DLL_MEMBER const char* VW_CALLING_CONV VW_GetTag(VW_EXAMPLE e);
 VW_DLL_MEMBER size_t VW_CALLING_CONV VW_GetFeatureNumber(VW_EXAMPLE e);
+VW_DLL_MEMBER float VW_CALLING_CONV VW_GetConfidence(VW_EXAMPLE e);
 VW_DLL_MEMBER VW_FEATURE VW_CALLING_CONV VW_GetFeatures(VW_HANDLE handle, VW_EXAMPLE e, size_t* plen);
 VW_DLL_MEMBER void VW_CALLING_CONV VW_ReturnFeatures(VW_FEATURE f);
 #ifdef USE_CODECVT
@@ -120,6 +123,8 @@ VW_DLL_MEMBER size_t VW_CALLING_CONV VW_Num_Weights(VW_HANDLE handle);
 VW_DLL_MEMBER size_t VW_CALLING_CONV VW_Get_Stride(VW_HANDLE handle);
 
 VW_DLL_MEMBER void VW_CALLING_CONV VW_SaveModel(VW_HANDLE handle);
+VW_DLL_MEMBER void VW_CALLING_CONV VW_CopyModelData(VW_HANDLE handle, VW_IOBUF* bufferHandle, char** outputData, size_t* outputSize);
+VW_DLL_MEMBER void VW_CALLING_CONV VW_FreeIOBuf(VW_IOBUF bufferHandle);
 
 #ifdef __cplusplus
 }