Added more streamlined interfaces for converting rendezvous ids

to/from strings and used these in the rendezvous code.  Improves
performance for ptb_word_lm slightly (saves several allocations and an
sscanf per CPU <-> GPU transfer).
Change: 115852277

3 files changed, 61 insertions, 0 deletions

diff --git a/tensorflow/core/lib/strings/numbers.cc b/tensorflow/core/lib/strings/numbers.cc
index 778545b44b..a60de543cc 100644
--- a/tensorflow/core/lib/strings/numbers.cc
+++ b/tensorflow/core/lib/strings/numbers.cc
@@ -15,6 +15,7 @@ limitations under the License.
 
 #include "tensorflow/core/lib/strings/numbers.h"
 
+#include <ctype.h>
 #include <float.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -237,6 +238,38 @@ bool StringToFp(const string& s, Fprint* fp) {
   }
 }
 
+StringPiece Uint64ToHexString(uint64 v, char* buf) {
+  static const char* hexdigits = "0123456789abcdef";
+  const int num_byte = 16;
+  buf[num_byte] = '\0';
+  for (int i = num_byte - 1; i >= 0; i--) {
+    buf[i] = hexdigits[v & 0xf];
+    v >>= 4;
+  }
+  return StringPiece(buf, num_byte);
+}
+
+bool HexStringToUint64(const StringPiece& s, uint64* result) {
+  uint64 v = 0;
+  if (s.empty()) {
+    return false;
+  }
+  for (int i = 0; i < s.size(); i++) {
+    char c = s[i];
+    if (c >= '0' && c <= '9') {
+      v = (v << 4) + (c - '0');
+    } else if (c >= 'a' && c <= 'f') {
+      v = (v << 4) + 10 + (c - 'a');
+    } else if (c >= 'A' && c <= 'F') {
+      v = (v << 4) + 10 + (c - 'A');
+    } else {
+      return false;
+    }
+  }
+  *result = v;
+  return true;
+}
+
 string HumanReadableNumBytes(int64 num_bytes) {
   if (num_bytes == kint64min) {
     // Special case for number with not representable negation.
diff --git a/tensorflow/core/lib/strings/numbers.h b/tensorflow/core/lib/strings/numbers.h
index 4dd0bcdec4..02903547a7 100644
--- a/tensorflow/core/lib/strings/numbers.h
+++ b/tensorflow/core/lib/strings/numbers.h
@@ -18,6 +18,7 @@ limitations under the License.
 
 #include <string>
 
+#include "tensorflow/core/lib/core/stringpiece.h"
 #include "tensorflow/core/platform/types.h"
 
 namespace tensorflow {
@@ -81,6 +82,16 @@ string FpToString(Fprint fp);
 // returns false.
 bool StringToFp(const string& s, Fprint* fp);
 
+// Convert a 64-bit fingerprint value to an ASCII representation that
+// is terminated by a '\0'.
+// Buf must point to an array of at least kFastToBufferSize characters
+StringPiece Uint64ToHexString(uint64 v, char* buf);
+
+// Attempt to parse a uint64 in the form encoded by FastUint64ToHexString.  If
+// successful, stores the value in *v and returns true.  Otherwise,
+// returns false.
+bool HexStringToUint64(const StringPiece& s, uint64* v);
+
 // Convert strings to 32bit integer values.
 // Leading and trailing spaces are allowed.
 // Return false with overflow or invalid input.
diff --git a/tensorflow/core/lib/strings/numbers_test.cc b/tensorflow/core/lib/strings/numbers_test.cc
index e583ffedb2..67fec856a1 100644
--- a/tensorflow/core/lib/strings/numbers_test.cc
+++ b/tensorflow/core/lib/strings/numbers_test.cc
@@ -41,6 +41,23 @@ TEST(FpToString, Ints) {
   EXPECT_FALSE(StringToFp("0000000000000000xyz", &dummy));
 }
 
+TEST(Uint64ToHexString, Ints) {
+  for (int s = 0; s < 64; s++) {
+    for (int delta = -1; delta <= 1; delta++) {
+      uint64 fp = (1ull << s) + delta;
+      char buf[kFastToBufferSize];
+      StringPiece s = Uint64ToHexString(fp, buf);
+      uint64 fp2;
+      EXPECT_TRUE(HexStringToUint64(s, &fp2));
+      EXPECT_EQ(fp, fp2) << s;
+    }
+  }
+  uint64 dummy;
+  EXPECT_FALSE(HexStringToUint64("", &dummy));
+  EXPECT_FALSE(HexStringToUint64("xyz", &dummy));
+  EXPECT_FALSE(HexStringToUint64("0000000000000000xyz", &dummy));
+}
+
 TEST(HumanReadableNumBytes, Bytes) {
   EXPECT_EQ("0B", HumanReadableNumBytes(0));
   EXPECT_EQ("4B", HumanReadableNumBytes(4));