Add Detach to TSharedData

add Detach to TSharedData

5 files changed, 36 insertions, 6 deletions

diff --git a/library/cpp/actors/util/contiguous_data.h b/library/cpp/actors/util/contiguous_data.h
index c52ef4b7d8..382b19f82c 100644
--- a/library/cpp/actors/util/contiguous_data.h
+++ b/library/cpp/actors/util/contiguous_data.h
@@ -639,7 +639,7 @@ class TContiguousData {
 
         NActors::TSharedData GetRawTrimmed(size_t size) const {
             NActors::TSharedData result = GetRaw<NActors::TSharedData>();
-            result.Trim(size);
+            result.TrimBack(size);
             return result;
         }
 
diff --git a/library/cpp/actors/util/shared_data.h b/library/cpp/actors/util/shared_data.h
index 6fdc9bf35f..8425738578 100644
--- a/library/cpp/actors/util/shared_data.h
+++ b/library/cpp/actors/util/shared_data.h
@@ -101,7 +101,7 @@ namespace NActors {
          * Underlying data is not reallocated
          * Returns trimmed amount in bytes
          */
-        size_t Trim(size_t size) noexcept {
+        size_t TrimBack(size_t size) noexcept {
             size_t trimmed = 0;
             if (Size_ > size) {
                 trimmed = Size_ - size;
@@ -115,6 +115,18 @@ namespace NActors {
         }
 
         /**
+         * Copies data to new allocated buffer if data is shared
+         * New container loses original owner
+         * Returns pointer to mutable buffer
+         */
+        char* Detach() {
+            if (IsShared()) {
+                *this = TSharedData::Copy(data(), size());
+            }
+            return Data_;
+        }
+
+        /**
          * Returns a view of underlying data starting with pos and up to len bytes
          */
         TStringBuf Slice(size_t pos = 0, size_t len = -1) const noexcept {
diff --git a/library/cpp/actors/util/shared_data_native_rope_backend_ut.cpp b/library/cpp/actors/util/shared_data_native_rope_backend_ut.cpp
index 443fc149da..4939403454 100644
--- a/library/cpp/actors/util/shared_data_native_rope_backend_ut.cpp
+++ b/library/cpp/actors/util/shared_data_native_rope_backend_ut.cpp
@@ -221,7 +221,7 @@ namespace NActors {
                 UNIT_ASSERT_EQUAL(dataCopy.data(), data.data());
                 rope.Insert(rope.End(), TRope(data));
                 rope.Insert(rope.End(), TRope(data));
-                dataCopy.Trim(10);
+                dataCopy.TrimBack(10);
                 UNIT_ASSERT_EQUAL(rope.GetSize(), data.size() * 3);
             }
             UNIT_ASSERT(data.IsPrivate());
diff --git a/library/cpp/actors/util/shared_data_rope_backend_ut.cpp b/library/cpp/actors/util/shared_data_rope_backend_ut.cpp
index 3ffe14a544..b2b4e04634 100644
--- a/library/cpp/actors/util/shared_data_rope_backend_ut.cpp
+++ b/library/cpp/actors/util/shared_data_rope_backend_ut.cpp
@@ -221,7 +221,7 @@ namespace NActors {
                 UNIT_ASSERT_EQUAL(dataCopy.data(), data.data());
                 rope.Insert(rope.End(), TRope(MakeIntrusive<TRopeSharedDataBackend>(data)));
                 rope.Insert(rope.End(), TRope(MakeIntrusive<TRopeSharedDataBackend>(data)));
-                dataCopy.Trim(10);
+                dataCopy.TrimBack(10);
                 UNIT_ASSERT_EQUAL(rope.GetSize(), data.size() * 3);
             }
             UNIT_ASSERT(data.IsPrivate());
diff --git a/library/cpp/actors/util/shared_data_ut.cpp b/library/cpp/actors/util/shared_data_ut.cpp
index 8ed0df6866..0a510122b4 100644
--- a/library/cpp/actors/util/shared_data_ut.cpp
+++ b/library/cpp/actors/util/shared_data_ut.cpp
@@ -43,6 +43,12 @@ namespace NActors {
             UNIT_ASSERT_VALUES_EQUAL(TString(data.Slice(1, 3)), TString("ell"));
             UNIT_ASSERT_VALUES_EQUAL(TString(data.Slice(1, 100)), TString("ello"));
             UNIT_ASSERT_VALUES_EQUAL(TString(data.Slice(0, 4)), TString("Hell"));
+
+            link = data;
+            UNIT_ASSERT(link.data() == data.data());
+            UNIT_ASSERT_VALUES_UNEQUAL(link.Detach(), data.data());
+            UNIT_ASSERT_EQUAL(data.size(), link.size());
+            UNIT_ASSERT_VALUES_EQUAL(TString(data.Slice()), TString(link.Slice()));
         }
 
         Y_UNIT_TEST(TrimBehavior) {
@@ -53,14 +59,14 @@ namespace NActors {
 
             // Trim to non-zero does not change addresses
             const char* ptr1 = data.data();
-            data.Trim(31);
+            data.TrimBack(31);
             const char* ptr2 = data.data();
 
             UNIT_ASSERT_VALUES_EQUAL(data.size(), 31u);
             UNIT_ASSERT(ptr1 == ptr2);
 
             // Trim to zero releases underlying data
-            data.Trim(0);
+            data.TrimBack(0);
 
             UNIT_ASSERT_VALUES_EQUAL(data.size(), 0u);
             UNIT_ASSERT(data.data() == nullptr);
@@ -179,6 +185,18 @@ namespace NActors {
 
             UNIT_ASSERT(owner.NextDeallocated() == ptr);
             UNIT_ASSERT(owner.NextDeallocated() == nullptr);
+
+            // Test Detach copies correctly and doesn't affect owned data
+            {
+                auto data = owner.Allocate(42);
+                auto disowned = data;
+                disowned.Detach();
+                UNIT_ASSERT(owner.NextDeallocated() == nullptr);
+            }
+
+            UNIT_ASSERT(owner.NextDeallocated() == ptr);
+            UNIT_ASSERT(owner.NextDeallocated() == nullptr);
+
         }
 
     }