Remove dangerous code

src/Columns/tests/gtest_weak_hash_32.cpp

@@ -26,9 +26,7 @@ using namespace DB;
 template <typename T>
 void checkColumn(
     const WeakHash32::Container & hash,
-    const PaddedPODArray<T> & eq_class,
-    size_t allowed_collisions = 0,
-    size_t max_collisions_to_print = 10)
+    const PaddedPODArray<T> & eq_class)
 {
     ASSERT_EQ(hash.size(), eq_class.size());
 
@@ -52,41 +50,6 @@ void checkColumn(
             }
         }
     }
-
-    /// Check have not many collisions.
-    {
-        std::unordered_map<UInt32, T> map;
-        size_t num_collisions = 0;
-
-        std::stringstream collisions_str;       // STYLE_CHECK_ALLOW_STD_STRING_STREAM
-        collisions_str.exceptions(std::ios::failbit);
-
-        for (size_t i = 0; i < eq_class.size(); ++i)
-        {
-            auto & val = eq_class[i];
-            auto it = map.find(hash[i]);
-
-            if (it == map.end())
-                map[hash[i]] = val;
-            else if (it->second != val)
-            {
-                ++num_collisions;
-
-                if (num_collisions <= max_collisions_to_print)
-                {
-                    collisions_str << "Collision:\n";
-                }
-
-                if (num_collisions > allowed_collisions)
-                {
-                    std::cerr << collisions_str.rdbuf();
-                    break;
-                }
-            }
-        }
-
-        ASSERT_LE(num_collisions, allowed_collisions);
-    }
 }
 
 TEST(WeakHash32, ColumnVectorU8)
@@ -374,10 +337,7 @@ TEST(WeakHash32, ColumnString2)
     WeakHash32 hash(col->size());
     col->updateWeakHash32(hash);
 
-    /// Now there is single collision between 'k' * 544 and 'q' * 2512 (which is calculated twice)
-    size_t allowed_collisions = 4;
-
-    checkColumn(hash.getData(), data, allowed_collisions);
+    checkColumn(hash.getData(), data);
 }
 
 TEST(WeakHash32, ColumnString3)
@@ -717,8 +677,7 @@ TEST(WeakHash32, ColumnTupleUInt64String)
     WeakHash32 hash(col_tuple->size());
     col_tuple->updateWeakHash32(hash);
 
-    size_t allowed_collisions = 8;
-    checkColumn(hash.getData(), eq, allowed_collisions);
+    checkColumn(hash.getData(), eq);
 }
 
 TEST(WeakHash32, ColumnTupleUInt64FixedString)
@@ -803,10 +762,5 @@ TEST(WeakHash32, ColumnTupleUInt64Array)
     WeakHash32 hash(col_tuple->size());
     col_tuple->updateWeakHash32(hash);
 
-    /// There are 2 collisions right now (repeated 2 times each):
-    /// (0, [array of size 1212 with values 7]) vs (0, [array of size 2265 with values 17])
-    /// (0, [array of size 558 with values 5]) vs (1, [array of size 879 with values 21])
-
-    size_t allowed_collisions = 8;
-    checkColumn(hash.getData(), eq_data, allowed_collisions);
+    checkColumn(hash.getData(), eq_data);
 }

src/Common/StudentTTest.cpp

@@ -6,6 +6,9 @@
 #include <sstream>
 #include <stdexcept>
 
+#include <IO/WriteBufferFromString.h>
+#include <IO/Operators.h>
+
 
 namespace
 {
@@ -153,19 +156,17 @@ std::pair<bool, std::string> StudentTTest::compareAndReport(size_t confidence_le
 
     double mean_confidence_interval = table_value * t_statistic;
 
-    std::stringstream ss;       // STYLE_CHECK_ALLOW_STD_STRING_STREAM
-    ss.exceptions(std::ios::failbit);
+    DB::WriteBufferFromOwnString out;
 
     if (mean_difference > mean_confidence_interval && (mean_difference - mean_confidence_interval > 0.0001)) /// difference must be more than 0.0001, to take into account connection latency.
     {
-        ss << "Difference at " << confidence_level[confidence_level_index] <<  "% confidence: ";
-        ss << std::fixed << std::setprecision(8) << "mean difference is " << mean_difference << ", but confidence interval is " << mean_confidence_interval;
-        return {false, ss.str()};
+        out << "Difference at " << confidence_level[confidence_level_index] <<  "% confidence: ";
+        out << "mean difference is " << mean_difference << ", but confidence interval is " << mean_confidence_interval;
+        return {false, out.str()};
     }
     else
     {
-        ss << "No difference proven at " << confidence_level[confidence_level_index] <<  "% confidence";
-        return {true, ss.str()};
+        out << "No difference proven at " << confidence_level[confidence_level_index] <<  "% confidence";
+        return {true, out.str()};
     }
 }
-

src/Daemon/BaseDaemon.cpp

@@ -358,10 +358,13 @@ private:
             /// NOTE: This still require memory allocations and mutex lock inside logger.
             ///       BTW we can also print it to stderr using write syscalls.
 
-            std::stringstream bare_stacktrace; // STYLE_CHECK_ALLOW_STD_STRING_STREAM
-            bare_stacktrace << "Stack trace:";
+            DB::WriteBufferFromOwnString bare_stacktrace;
+            DB::writeString("Stack trace:", bare_stacktrace);
             for (size_t i = stack_trace.getOffset(); i < stack_trace.getSize(); ++i)
-                bare_stacktrace << ' ' << stack_trace.getFramePointers()[i];
+            {
+                DB::writeChar(' ', bare_stacktrace);
+                DB::writePointerHex(stack_trace.getFramePointers()[i], bare_stacktrace);
+            }
 
             LOG_FATAL(log, fmt::runtime(bare_stacktrace.str()));
         }