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LocalStore::addToStoreFromDump copy in chunks

Browse source 
Rather than copying byte-by-byte, we let the coroutine know how much
data we would like it to send back to us.
This commit is contained in:
John Ericson 2020-07-11 23:40:49 +00:00
parent 9de96ef7d4
commit 592851fb67
4 changed files with 40 additions and 22 deletions
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33
src/libutil/serialise.cc
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@ -165,35 +165,43 @@ size_t StringSource::read(unsigned char * data, size_t len)
#endif
std::unique_ptr<Source> sinkToSource(
std::function<void(Sink &)> fun,
std::function<void(Sink &, size_t &)> fun,
std::function<void()> eof)
{
struct SinkToSource : Source
{
typedef boost::coroutines2::coroutine<std::string> coro_t;
typedef boost::coroutines2::coroutine<std::basic_string<uint8_t>> coro_t;
std::function<void(Sink &)> fun;
std::function<void(Sink &, size_t &)> fun;
std::function<void()> eof;
std::optional<coro_t::pull_type> coro;
bool started = false;
SinkToSource(std::function<void(Sink &)> fun, std::function<void()> eof)
/* It would be nicer to have the co-routines have both args and a
return value, but unfortunately that was removed from Boost's
implementation for some reason, so we use some extra state instead.
*/
size_t wanted = 0;
SinkToSource(std::function<void(Sink &, size_t &)> fun, std::function<void()> eof)
: fun(fun), eof(eof)
{
}
std::string cur;
std::basic_string<uint8_t> cur;
size_t pos = 0;
size_t read(unsigned char * data, size_t len) override
{
if (!coro)
wanted = len < cur.size() ? 0 : len - cur.size();
if (!coro) {
coro = coro_t::pull_type([&](coro_t::push_type & yield) {
LambdaSink sink([&](const unsigned char * data, size_t len) {
if (len) yield(std::string((const char *) data, len));
LambdaSink sink([&](const uint8_t * data, size_t len) {
if (len) yield(std::basic_string<uint8_t> { data, len });
});
fun(sink);
fun(sink, wanted);
});
}
if (!*coro) { eof(); abort(); }
@ -203,11 +211,10 @@ std::unique_ptr<Source> sinkToSource(
pos = 0;
}
auto n = std::min(cur.size() - pos, len);
memcpy(data, (unsigned char *) cur.data() + pos, n);
pos += n;
auto numCopied = cur.copy(data, len, pos);
pos += numCopied;
return n;
return numCopied;
}
};