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Improved buffer management in serializer #139

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Merged
ashtum merged 1 commit into from
Jun 18, 2025
Merged

Improved buffer management in serializer #139

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7 changes: 4 additions & 3 deletions include/boost/http_proto/serializer.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -444,10 +444,11 @@ struct serializer::stream
class serializer::const_buf_gen_base
{
public:
// Next non-empty buffer
// Returns the next non-empty buffer,
// or an empty buffer if none remain.
virtual
buffers::const_buffer
operator()() = 0;
next() = 0;

// Size of remaining buffers
virtual
Expand Down Expand Up @@ -487,7 +488,7 @@ class serializer::const_buf_gen
}

const_buffer
operator()() override
next() override
{
while(current_ != buffers::end(cbs_))
{
Expand Down
51 changes: 30 additions & 21 deletions src/detail/impl/filter.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -30,20 +30,44 @@ process_impl(
results
{
results rv;

auto it_o = buffers::begin(out);
auto it_i = buffers::begin(in);

if( it_o == buffers::end(out) ||
it_i == buffers::end(in) )
return rv;
auto ob = [&]() -> buffers::mutable_buffer
{
if( it_o != buffers::end(out) )
return *it_o++;
return {};
}();

buffers::const_buffer ib;

auto ob = *it_o++;
auto ib = *it_i++;
for(;;)
{
while( ib.size() == 0 )
{
if( it_i == buffers::end(in) )
{
if( more )
return rv;

// if more == false we return only
// when output buffers are full.
break;
}
else
{
ib = *it_i++;
}
}

// empty input buffers may be passed, and
// this is intentional and valid.
results rs = process_impl(ob, ib, more);
results rs = process_impl(
ob,
ib,
more || it_i != buffers::end(in));

rv.out_bytes += rs.out_bytes;
rv.in_bytes += rs.in_bytes;
Expand All @@ -62,21 +86,6 @@ process_impl(
return rv;
ob = *it_o++;
}

if( ib.size() == 0 )
{
if( it_i == buffers::end(in) )
{
// if `more == false` we return only
// when `out` buffers are full.
if( more )
return rv;
}
else
{
ib = *it_i++;
}
}
}
}

Expand Down
170 changes: 99 additions & 71 deletions src/serializer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -286,19 +286,11 @@ void
serializer::
reset() noexcept
{
ws_.clear();
filter_ = nullptr;

cb0_ = {};
tmp_ = {};

more_input_ = false;
is_done_ = false;
is_header_done_ = false;
is_chunked_ = false;
needs_exp100_continue_ = false;
filter_done_ = false;

ws_.clear();
}

//------------------------------------------------
Expand Down Expand Up @@ -343,23 +335,23 @@ prepare() ->
prepped_.slide_to_front();
while(prepped_.capacity() != 0)
{
auto buf = buf_gen_->operator()();
auto buf = buf_gen_->next();
if(buf.size() != 0)
{
prepped_.append(buf);
}
else // buf_gen_ is empty
{
// crlf and final chunk
if(tmp_.size() != 0)
// append crlf and final chunk
if(is_chunked_)
{
prepped_.append(tmp_);
tmp_ = {};
more_input_ = false;
}
break;
}
}
if(buf_gen_->is_empty() && tmp_.size() == 0)
if(buf_gen_->is_empty() && !is_chunked_)
more_input_ = false;
}
return const_buffers_type(
Expand All @@ -377,16 +369,18 @@ prepare() ->
if(apndr.is_full())
break;

auto rs = source_->read(
const auto rs = source_->read(
apndr.prepare());

if(rs.ec.failed())
{
is_done_ = true;
BOOST_HTTP_PROTO_RETURN_EC(rs.ec);
return rs.ec;
}

more_input_ = !rs.finished;
if(rs.finished)
more_input_ = false;

apndr.commit(rs.bytes, more_input_);
break;
}
Expand All @@ -400,90 +394,121 @@ prepare() ->
}
else // filter
{
if(st_ == style::empty)
switch(st_)
{
case style::empty:
return const_buffers_type(
prepped_.begin(),
prepped_.size());

auto get_input = [&]()
case style::buffers:
{
if(st_ == style::buffers)
appender apndr(cb0_, is_chunked_);
while(!apndr.is_full() && !filter_done_)
{
// TODO: for efficiency of deflator, we might
// need to return multiple buffers at once
if(tmp_.size() == 0)
if(more_input_ && tmp_.size() == 0)
{
tmp_ = buf_gen_->operator()();
more_input_ = !buf_gen_->is_empty();
tmp_ = buf_gen_->next();
if(tmp_.size() == 0) // buf_gen_ is empty
more_input_ = false;
}
return buffers::
const_buffer_pair{ tmp_, {} };
}

BOOST_ASSERT(
st_ == style::source ||
st_ == style::stream);
const auto rs = filter_->process(
apndr.prepare(),
tmp_,
more_input_);

if(rs.ec.failed())
{
is_done_ = true;
return rs.ec;
}

tmp_ = buffers::sans_prefix(tmp_, rs.in_bytes);
apndr.commit(rs.out_bytes, !rs.finished);

if(st_ == style::source &&
more_input_ &&
cb1_.capacity() != 0)
{
// TODO: handle source error
auto rs = source_->read(
cb1_.prepare(cb1_.capacity()));
if(rs.finished)
more_input_ = false;
cb1_.commit(rs.bytes);
filter_done_ = true;
}
break;
}

return cb1_.data();
};

auto consume = [&](std::size_t n)
case style::source:
{
if(st_ == style::buffers)
appender apndr(cb0_, is_chunked_);
while(!apndr.is_full() && !filter_done_)
{
tmp_ = buffers::sans_prefix(
tmp_, n);
return;
if(more_input_ && cb1_.capacity() != 0)
{
const auto rs = source_->read(
cb1_.prepare(cb1_.capacity()));
if(rs.ec.failed())
{
is_done_ = true;
return rs.ec;
}
if(rs.finished)
more_input_ = false;
cb1_.commit(rs.bytes);
}

const auto rs = filter_->process(
apndr.prepare(),
cb1_.data(),
more_input_);

if(rs.ec.failed())
{
is_done_ = true;
return rs.ec;
}

cb1_.consume(rs.in_bytes);
apndr.commit(rs.out_bytes, !rs.finished);

if(rs.finished)
filter_done_ = true;
}
BOOST_ASSERT(
st_ == style::source ||
st_ == style::stream);
cb1_.consume(n);
};

// handles chunked payloads automatically
appender apndr(cb0_, is_chunked_);
for(;;)
break;
}

case style::stream:
{
if(apndr.is_full())
appender apndr(cb0_, is_chunked_);

if(apndr.is_full() || filter_done_)
break;

auto cbs = get_input();
// The stream object is expected to
// have already populated cb1_
if(more_input_ && cb1_.size() == 0)
{
if(!prepped_.empty())
break;

if(more_input_ && buffers::size(cbs) == 0)
break;
BOOST_HTTP_PROTO_RETURN_EC(
error::need_data);
}

auto rs = filter_->process(
const auto rs = filter_->process(
apndr.prepare(),
cbs,
cb1_.data(),
more_input_);

if(rs.ec.failed())
{
is_done_ = true;
BOOST_HTTP_PROTO_RETURN_EC(rs.ec);
return rs.ec;
}

consume(rs.in_bytes);
cb1_.consume(rs.in_bytes);
apndr.commit(rs.out_bytes, !rs.finished);

if(rs.finished)
{
filter_done_ = true;
break;
}

break;
}
}
}

Expand Down Expand Up @@ -623,6 +648,7 @@ start_empty(
}

prepped_[0] = { m.ph_->cbuf, m.ph_->size };
more_input_ = false;
}

void
Expand Down Expand Up @@ -654,7 +680,7 @@ start_buffers(
std::generate(
prepped_.begin() + 1,
prepped_.end(),
std::ref(*buf_gen_));
[this](){ return buf_gen_->next(); });
more_input_ = !buf_gen_->is_empty();
return;
}
Expand All @@ -676,6 +702,7 @@ start_buffers(

prepped_[0] = { m.ph_->cbuf, m.ph_->size };
prepped_[1] = final_chunk;
more_input_ = false;
return;
}

Expand Down Expand Up @@ -717,14 +744,14 @@ start_buffers(
std::generate(
prepped_.begin() + 2,
prepped_.end() - 1,
std::ref(*buf_gen_));
[this](){ return buf_gen_->next(); });

more_input_ = !buf_gen_->is_empty();
// assigning the last slot
if(more_input_)
{
prepped_[prepped_.size() - 1] =
buf_gen_->operator()();
buf_gen_->next();

// deferred until buf_gen_ is drained
tmp_ = crlf_and_final_chunk;
Expand Down Expand Up @@ -758,6 +785,7 @@ start_buffers(
}

prepped_[0] = { m.ph_->cbuf, m.ph_->size };
tmp_ = {};
more_input_ = !buf_gen_->is_empty();
}

Expand Down
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