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Using std::vector::assign in stead of resize + memcpy
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Because std::vector::resize adds an unnecessary initialization step
this performs worse than using assign

Signed-off-by: Martijn Reicher <[email protected]>
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@reicheratwork
reicheratwork committed Jan 25, 2023
1 parent af5e2af commit 72a1afc
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Showing 2 changed files with 63 additions and 15 deletions.
33 changes: 33 additions & 0 deletions src/ddscxx/include/org/eclipse/cyclonedds/core/cdr/cdr_stream.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -971,6 +971,39 @@ bool max_string(S& str, const T& max_sz, size_t N)
return true;
}

/**
* @brief
* Sequence of base types read function.
*
* This is called when a resize + memcpy is way less efficient than an assign,
* as this skips the default initialization of entities in the sequence.
*
* @param[in, out] str The stream being read from.
* @param[in] toread The sequence being read into.
* @param[in] N Number of base entities to read.
*
* @return Whether the operation was completed succesfully.
*/
template<typename S, template<typename,typename> class V, typename T, typename A, std::enable_if_t<std::is_base_of<cdr_stream, S>::value && std::is_arithmetic<T>::value && !std::is_same<T,bool>::value, bool> = true >
bool read(S& str, V<T,A> &toread, size_t N)
{
if (str.position() == SIZE_MAX
|| !str.align(sizeof(T), false)
|| !str.bytes_available(sizeof(T)*N))
return false;

auto ptr = reinterpret_cast<const T*>(str.get_cursor());
toread.assign(ptr, ptr+N);
str.incr_position(N*sizeof(T));

if (str.swap_endianness()) {
for (auto &e:toread)
byte_swap(e);
}

return true;
}

}
}
}
Expand Down
45 changes: 30 additions & 15 deletions src/idlcxx/src/streamers.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -365,7 +365,8 @@ write_base_type_streaming_functions(
const idl_type_spec_t* type_spec,
const char* accessor,
const char* read_accessor,
instance_location_t loc)
instance_location_t loc,
bool skip_reads)
{
const char* fmt =
" if (!{T}(streamer, %1$s))\n"
Expand All @@ -390,7 +391,7 @@ write_base_type_streaming_functions(
}

if (multi_putf(streams, CONST, fmt, accessor)
|| multi_putf(streams, READ, rfmt, read_accessor))
|| (!skip_reads && multi_putf(streams, READ, rfmt, read_accessor)))
return IDL_RETCODE_NO_MEMORY;

return IDL_RETCODE_OK;
Expand All @@ -402,24 +403,25 @@ write_streaming_functions(
const idl_type_spec_t* type_spec,
const char* accessor,
const char* read_accessor,
instance_location_t loc)
instance_location_t loc,
bool skip_reads)
{
if (idl_is_alias(type_spec)) {
const idl_typedef_t *td = idl_parent(type_spec);
const idl_type_spec_t *ts = idl_type_spec(td);
//if this is an alias for a bare type, just use the bare type
if (!idl_is_array(td->declarators) && !idl_is_sequence(ts) && (idl_is_base_type(ts) || idl_is_string(ts)))
return write_streaming_functions(streams, ts, accessor, read_accessor, loc);
return write_streaming_functions(streams, ts, accessor, read_accessor, loc, skip_reads);
else
return write_typedef_streaming_functions(streams, type_spec, accessor, read_accessor);
} else if (idl_is_forward(type_spec)) {
return write_streaming_functions(streams, idl_type_spec(type_spec), accessor, read_accessor, loc);
return write_streaming_functions(streams, idl_type_spec(type_spec), accessor, read_accessor, loc, skip_reads);
} else if (idl_is_string(type_spec)) {
return write_string_streaming_functions(streams, type_spec, accessor, read_accessor);
} else if (idl_is_union(type_spec) || idl_is_struct(type_spec)) {
return write_constructed_type_streaming_functions(streams, accessor, read_accessor);
} else {
return write_base_type_streaming_functions(streams, type_spec, accessor, read_accessor, loc);
return write_base_type_streaming_functions(streams, type_spec, accessor, read_accessor, loc, skip_reads);
}
}

Expand All @@ -439,7 +441,8 @@ sequence_writes(const idl_pstate_t* pstate,
size_t depth,
const char* accessor,
const char* read_accessor,
instance_location_t loc)
instance_location_t loc,
bool skip_reads)
{
const idl_type_spec_t *type_spec = seq->type_spec;

Expand All @@ -457,7 +460,7 @@ sequence_writes(const idl_pstate_t* pstate,
if (IDL_PRINTA(&type, get_cpp11_type, type_spec, streams->generator) < 0
|| multi_putf(streams, MOVE | MAX, mfmt, type, depth)
|| multi_putf(streams, WRITE, sfmt, accessor, depth)
|| multi_putf(streams, READ, sfmt, read_accessor, depth))
|| (!skip_reads && multi_putf(streams, READ, sfmt, read_accessor, depth)))
return IDL_RETCODE_NO_MEMORY;

return IDL_RETCODE_OK;
Expand All @@ -483,7 +486,7 @@ sequence_writes(const idl_pstate_t* pstate,
if (unroll_sequence (pstate, streams, (idl_sequence_t*)type_spec, depth + 1, new_accessor, new_read_accessor, loc))
return IDL_RETCODE_NO_MEMORY;
} else {
if (write_streaming_functions (streams, type_spec, new_accessor, new_read_accessor, loc))
if (write_streaming_functions (streams, type_spec, new_accessor, new_read_accessor, loc, skip_reads))
return IDL_RETCODE_NO_MEMORY;
}

Expand Down Expand Up @@ -513,7 +516,7 @@ unroll_sequence(const idl_pstate_t* pstate,
" return false;\n";
static const char* fmt1 =
" {\n"
" uint32_t se_%1$u = uint32_t(%2$s.size());\n";
" uint32_t se_%1$u(static_cast<uint32_t>(%2$s.size()));\n";
static const char* length_check =
" if (se_%1$u > %2$u &&\n"
" streamer.status(serialization_status::{T}_bound_exceeded))\n"
Expand All @@ -523,23 +526,35 @@ unroll_sequence(const idl_pstate_t* pstate,
" return false;\n";
static const char* rfmt =
" %1$s.resize(se_%2$u);\n";
static const char* rfmt2 =
" if (!read(streamer,%1$s,se_%2$u))\n"
" return false;\n";
static const char* mfmt =
" {\n"
" uint32_t se_%1$u = %2$u;\n";
static const char* rfmt3 =
" {\n"
" uint32_t se_%1$u(0);\n";

const idl_type_spec_t *root_type_spec = idl_strip(seq->type_spec, IDL_STRIP_ALIASES | IDL_STRIP_FORWARD);
if (multi_putf(streams, ALL, consec_start_fmt, idl_is_base_type(root_type_spec) && !idl_is_array(root_type_spec) ? "true" : "false"))
return IDL_RETCODE_NO_MEMORY;

if (multi_putf(streams, READ, fmt1, depth, read_accessor)
bool skip_reads = !idl_is_sequence(seq->type_spec) && idl_is_base_type(root_type_spec) && !(idl_mask(root_type_spec) == IDL_BOOL);

if (multi_putf(streams, READ, rfmt3, depth)
|| multi_putf(streams, (WRITE | MOVE), fmt1, depth, accessor)
|| multi_putf(streams, MAX, mfmt, depth, maximum)
|| (maximum && multi_putf(streams, NOMAX, length_check, depth, maximum))
|| multi_putf(streams, ALL, fmt2, depth)
|| multi_putf(streams, READ, rfmt, read_accessor, depth))
|| (maximum && multi_putf(streams, NOMAX, length_check, depth, maximum)))
return IDL_RETCODE_NO_MEMORY;

if (!skip_reads && multi_putf(streams, READ, rfmt, read_accessor, depth))
return IDL_RETCODE_NO_MEMORY;
else if (skip_reads && multi_putf(streams, READ, rfmt2, read_accessor, depth))
return IDL_RETCODE_NO_MEMORY;

if (sequence_writes(pstate, streams, seq, depth, accessor, read_accessor, loc))
if (sequence_writes(pstate, streams, seq, depth, accessor, read_accessor, loc, skip_reads))
return IDL_RETCODE_NO_MEMORY;

//close sequence
Expand Down Expand Up @@ -655,7 +670,7 @@ process_entity(
if (unroll_sequence(pstate, streams, (idl_sequence_t*)type_spec, 1, accessor, read_accessor, loc))
return IDL_RETCODE_NO_MEMORY;
} else {
if (write_streaming_functions(streams, type_spec, accessor, read_accessor, loc))
if (write_streaming_functions(streams, type_spec, accessor, read_accessor, loc, false))
return IDL_RETCODE_NO_MEMORY;
}

Expand Down

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