[Embedding] Support immutable EmbeddingVariable in inference mode.

tensorflow/core/framework/embedding/embedding_filter.h

@@ -45,6 +45,18 @@ class EmbeddingFilter {
  public:
   virtual void LookupOrCreate(K key, V* val, const V* default_value_ptr,
                                ValuePtr<V>** value_ptr, int count) = 0;
+
+  virtual void Lookup(EV* ev, K key, V* val, const V* default_value_ptr) {
+    ValuePtr<V>* value_ptr = nullptr;
+    Status s = ev->LookupKey(key, &value_ptr);
+    if (s.ok()) {
+      V* mem_val = ev->LookupPrimaryEmb(value_ptr);
+      memcpy(val, mem_val, sizeof(V) * ev->ValueLen());
+    } else {
+      memcpy(val, default_value_ptr, sizeof(V) * ev->ValueLen());
+    }
+  }
+
   virtual Status LookupOrCreateKey(K key, ValuePtr<V>** val, bool* is_filter) = 0;
 
   virtual int64 GetFreq(K key, ValuePtr<V>* value_ptr) = 0;

tensorflow/core/framework/embedding/embedding_var.h

@@ -99,6 +99,10 @@ class EmbeddingVar : public ResourceBase {
     return is_initialized_;
   }
 
+  Status LookupKey(K key, ValuePtr<V>** value_ptr) {
+    return storage_manager_->Get(key, value_ptr);
+  }
+
   Status LookupOrCreateKey(K key, ValuePtr<V>** value_ptr, bool* is_filter) {
     return filter_->LookupOrCreateKey(key, value_ptr, is_filter);
   }
@@ -127,6 +131,11 @@ class EmbeddingVar : public ResourceBase {
     return filter_->GetFreq(key);
   }
 
+  void Lookup(K key, V* val, V* default_v)  {
+    const V* default_value_ptr = (default_v == nullptr) ? default_value_ : default_v;
+    filter_->Lookup(this, key, val, default_value_ptr);
+  }
+
   void LookupOrCreate(K key, V* val, V* default_v, int count = 1)  {
     const V* default_value_ptr = (default_v == nullptr) ? default_value_ : default_v;
     ValuePtr<V>* value_ptr = nullptr;

tensorflow/core/framework/embedding/multilevel_embedding.h

@@ -223,6 +223,18 @@ class StorageManager {
     }
   }
 
+  Status Get(K key, ValuePtr<V>** value_ptr) {
+    Status s;
+    int level = 0;
+    for (; level < hash_table_count_; ++level) {
+      s = kvs_[level].first->Lookup(key, value_ptr);
+      if (s.ok()) {
+        break;
+      }
+    }
+    return s;
+  }
+
   Status GetOrCreate(K key, ValuePtr<V>** value_ptr, size_t size) {
     bool found = false;
     int level = 0;

tensorflow/core/kernels/kv_variable_ops.cc

@@ -52,6 +52,7 @@ using GPUDevice = Eigen::GpuDevice;
 namespace {
 const int64 kEmbeddingVarUseDB = -214;
 const int64 kInitializableEmbeddingVarUseDB = -215;
+const char* kInferenceMode = "INFERENCE_MODE";
 }
 
 #define REGISTER_KV_VAR_HANDLE(ktype, vtype)                           \
@@ -370,6 +371,10 @@ template <typename TKey, typename TValue>
 class KvResourceGatherOp : public OpKernel {
  public:
   explicit KvResourceGatherOp(OpKernelConstruction* c) : OpKernel(c) {
+    OP_REQUIRES_OK(c, c->GetAttr("is_inference", &is_inference_));
+    bool is_inference;
+    TF_CHECK_OK(ReadBoolFromEnvVar(kInferenceMode, false, &is_inference));
+    is_inference_ |= is_inference;
     OP_REQUIRES_OK(c,
         c->GetAttr("is_use_default_value_tensor",
           &is_use_default_value_tensor_));
@@ -393,6 +398,17 @@ class KvResourceGatherOp : public OpKernel {
         return 1;
       };
     }
+    if (!is_inference_) {
+      lookup_fn_ = [](EmbeddingVar<TKey, TValue>* ev, TKey key,
+                      TValue* val, TValue* default_v, int count) {
+        ev->LookupOrCreate(key, val, default_v, count);
+      };
+    } else {
+      lookup_fn_ = [](EmbeddingVar<TKey, TValue>* ev, TKey key,
+                      TValue* val, TValue* default_v, int count) {
+        ev->Lookup(key, val, default_v);
+      };
+    }
   }
 
   void Compute(OpKernelContext* c) override {
@@ -443,7 +459,7 @@ class KvResourceGatherOp : public OpKernel {
               default_v, indices_flat(i), i, ev->GetDefaultValueDim(),
               ev->ValueLen());
           int32 count = get_count_fn_(counts, i);
-          ev->LookupOrCreate(indices_flat(i),
+          lookup_fn_(ev, indices_flat(i),
               out_base + i * slice_elems, default_v_ptr, count);
         }
       };
@@ -463,9 +479,12 @@ class KvResourceGatherOp : public OpKernel {
 
   private:
     bool is_use_default_value_tensor_;
+    bool is_inference_;
     std::function<
       TValue*(TValue*, TKey, int64, int64, int64)> get_default_v_fn_;
     std::function<int32(int32*, int64)> get_count_fn_;
+    std::function<void(EmbeddingVar<TKey, TValue>* ev,
+      TKey key, TValue* val, TValue* default_v, int count)> lookup_fn_;
 };
 
 #define REGISTER_GATHER_FULL(dev, ktype, vtype)                   \

tensorflow/core/ops/kv_variable_ops.cc

@@ -231,6 +231,7 @@ REGISTER_OP("KvResourceGatherV1")
     .Input("counts: counts_type")
     .Attr("validate_indices: bool = true")
     .Attr("is_use_default_value_tensor: bool = false")
+    .Attr("is_inference: bool = false")
     .Output("output: dtype")
     .Attr("dtype: type")
     .Attr("Tkeys: {int64,int32,string}")
@@ -281,6 +282,7 @@ REGISTER_OP("KvResourceGather")
     .Output("output: dtype")
     .Attr("dtype: type")
     .Attr("Tkeys: {int64,int32,string}")
+    .Attr("is_inference: bool = false")
     .SetShapeFn([](InferenceContext* c) {
       ShapeAndType handle_shape_and_type;
       TF_RETURN_IF_ERROR(

tensorflow/python/ops/embedding_variable_ops_test.py

@@ -16,6 +16,7 @@
 
 from six.moves import xrange  # pylint: disable=redefined-builtin
 
+from tensorflow.core.framework import attr_value_pb2
 from tensorflow.python.framework import ops
 from tensorflow.python.framework import test_util
 from tensorflow.python.ops import string_ops