C++ Client: vendor the "fmt" project and start to use it

cpp-client/deephaven/dhcore/CMakeLists.txt

@@ -27,7 +27,7 @@ set(ALL_FILES
     src/ticking/shift_processor.cc
     src/ticking/space_mapper.cc
     src/ticking/ticking.cc
-        src/utility/cython_support.cc
+    src/utility/cython_support.cc
     src/utility/utility.cc
 
     include/private/deephaven/dhcore/ticking/immer_table_state.h
@@ -49,7 +49,7 @@ set(ALL_FILES
     include/public/deephaven/dhcore/container/row_sequence.h
     include/public/deephaven/dhcore/ticking/barrage_processor.h
     include/public/deephaven/dhcore/ticking/ticking.h
-        include/public/deephaven/dhcore/utility/cython_support.h
+    include/public/deephaven/dhcore/utility/cython_support.h
     include/public/deephaven/dhcore/utility/utility.h
 
     flatbuf/deephaven/flatbuf/Barrage_generated.h
@@ -73,7 +73,21 @@ set(ALL_FILES
     third_party/flatbuffers/include/flatbuffers/verifier.h
 
     third_party/roaring/include/roaring/roaring.c
-    )
+
+    third_party/fmt/include/fmt/args.h
+    third_party/fmt/include/fmt/chrono.h
+    third_party/fmt/include/fmt/color.h
+    third_party/fmt/include/fmt/compile.h
+    third_party/fmt/include/fmt/core.h
+    third_party/fmt/include/fmt/format-inl.h
+    third_party/fmt/include/fmt/format.h
+    third_party/fmt/include/fmt/os.h
+    third_party/fmt/include/fmt/ostream.h
+    third_party/fmt/include/fmt/printf.h
+    third_party/fmt/include/fmt/ranges.h
+    third_party/fmt/include/fmt/std.h
+    third_party/fmt/include/fmt/xchar.h
+)
 
 add_library(dhcore_objlib OBJECT ${ALL_FILES})
 # In order to make a shared library suitable for Cython.
@@ -83,6 +97,7 @@ target_compile_options(dhcore_objlib PRIVATE -Wall -Werror -Wno-deprecated-decla
 
 target_include_directories(dhcore_objlib PRIVATE include/private)
 target_include_directories(dhcore_objlib PRIVATE third_party/flatbuffers/include)
+target_include_directories(dhcore_objlib PRIVATE third_party/fmt/include)
 target_include_directories(dhcore_objlib PRIVATE third_party/roaring/include)
 target_include_directories(dhcore_objlib PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include/public>)
 
@@ -104,6 +119,7 @@ add_library(dhcore SHARED $<TARGET_OBJECTS:dhcore_objlib>)
 # TODO: How to avoid repetition here for target_include_directories?
 target_include_directories(dhcore PRIVATE include/private)
 target_include_directories(dhcore PRIVATE third_party/flatbuffers/include)
+target_include_directories(dhcore PRIVATE third_party/fmt/include)
 target_include_directories(dhcore PRIVATE third_party/roaring/include)
 target_include_directories(dhcore PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include/public>)
 target_link_libraries(dhcore PUBLIC ${object_link_libs})

cpp-client/deephaven/dhcore/src/utility/utility.cc

@@ -8,12 +8,18 @@
 #include <string>
 #include <vector>
 
+#define FMT_HEADER_ONLY
+#include "fmt/chrono.h"
+#include "fmt/core.h"
+
 #ifdef __GNUG__
 #include <cstdlib>
 #include <memory>
 #include <cxxabi.h>
 #endif
 
+static_assert(FMT_VERSION >= 100000);
+
 namespace deephaven::dhcore::utility {
 
 namespace {
@@ -196,20 +202,16 @@ void dumpTillPercentOrEnd(std::ostream &result, const char **fmt) {
 }  // namespace
 
 std::string EpochMillisToStr(int64_t epoch_millis) {
-  time_t time_secs = epoch_millis / 1000;
-  auto millis = epoch_millis % 1000;
-  struct tm tm = {};
-  localtime_r(&time_secs, &tm);
-  char date_buffer[32];  // ample
-  char millis_buffer[32];  // ample
-  char tz_buffer[32];  // ample
-  strftime(date_buffer, sizeof(date_buffer), "%FT%T", &tm);
-  snprintf(millis_buffer, sizeof(millis_buffer), ".%03zd", millis);
-  strftime(tz_buffer, sizeof(tz_buffer), "%z", &tm);
-
-  SimpleOstringstream s;
-  s << date_buffer << millis_buffer << tz_buffer;
-  return std::move(s.str());
+  std::chrono::milliseconds ms(epoch_millis);
+  // Make a system_clock with a resolution of milliseconds so that the date is formatted with 3
+  // digits of fractional precision in the seconds field. Note also that system_clock is assumed by
+  // fmt to be UTC (this is what we want).
+  auto tp = std::chrono::time_point<std::chrono::system_clock, std::chrono::milliseconds>(ms);
+  // %F - Equivalent to %Y-%m-%d, e.g. “1955-11-12”.
+  // T - literal 'T'
+  // %T - Equivalent to %H:%M:%S
+  // Z - literal 'Z'
+  return fmt::format("{:%FT%TZ}", tp);
 }
 
 std::int64_t
@@ -242,9 +244,7 @@ std::string demangle(const char* name) {
 #endif
 
 std::string ObjectId(const std::string &class_short_name, void *this_ptr) {
-  SimpleOstringstream s;
-  s << class_short_name << '(' << this_ptr << ')';
-  return std::move(s.str());
+  return fmt::format("{}({})", class_short_name, this_ptr);
 }
 
 std::string

cpp-client/deephaven/dhcore/third_party/fmt/.clang-format

@@ -0,0 +1,8 @@
+# Run manually to reformat a file:
+# clang-format -i --style=file <file>
+Language: Cpp
+BasedOnStyle: Google
+IndentPPDirectives: AfterHash
+IndentCaseLabels: false
+AlwaysBreakTemplateDeclarations: false
+DerivePointerAlignment: false