SERVER-23332 Expose query plan cache key in system.profile entry and query log lines

3 files changed, 17 insertions, 0 deletions

diff --git a/src/mongo/util/hex.cpp b/src/mongo/util/hex.cpp
index 2d4a563c05b..48f433c388a 100644
--- a/src/mongo/util/hex.cpp
+++ b/src/mongo/util/hex.cpp
@@ -90,6 +90,11 @@ std::string integerToHex<unsigned long long>(unsigned long long val) {
     return integerToHexDef(val);
 }
 
+std::string unsignedIntToFixedLengthHex(uint32_t val) {
+    char buf[9];
+    invariant(snprintf(buf, 9, "%08X", val) == 8);
+    return std::string(buf, 8);
+}
 
 std::string hexdump(const char* data, unsigned len) {
     verify(len < 1000000);
diff --git a/src/mongo/util/hex.h b/src/mongo/util/hex.h
index 382eb0bd86c..550fecc4cd5 100644
--- a/src/mongo/util/hex.h
+++ b/src/mongo/util/hex.h
@@ -111,6 +111,11 @@ inline std::string toHexLower(const void* inRaw, int len) {
     return out.str();
 }
 
+/**
+ * Returns the hex value with a fixed width of 8 chatacters.
+ */
+std::string unsignedIntToFixedLengthHex(uint32_t val);
+
 /* @return a dump of the buffer as hex byte ascii output */
 std::string hexdump(const char* data, unsigned len);
 }
diff --git a/src/mongo/util/stringutils_test.cpp b/src/mongo/util/stringutils_test.cpp
index 80bbfc5db10..a156471dc57 100644
--- a/src/mongo/util/stringutils_test.cpp
+++ b/src/mongo/util/stringutils_test.cpp
@@ -194,6 +194,13 @@ TEST(StringUtilsTest, VariousConversions) {
                   integerToHex(std::numeric_limits<long long>::min()));
 }
 
+TEST(StringUtilsTest, unsignedFixedLengthHex) {
+    ASSERT_EQUALS(unsignedIntToFixedLengthHex(std::numeric_limits<uint32_t>::max()),
+                  std::string("FFFFFFFF"));
+    ASSERT_EQUALS(unsignedIntToFixedLengthHex(0), std::string("00000000"));
+    ASSERT_EQUALS(unsignedIntToFixedLengthHex(123), std::string("0000007B"));
+}
+
 TEST(StringUtilsTest, CanParseZero) {
     boost::optional<size_t> result = parseUnsignedBase10Integer("0");
     ASSERT(result && *result == 0);