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Small fix and more comments

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This commit is contained in:
kssenii 2021-10-01 11:38:58 +03:00
parent 6f49ebe6e7
commit 55972db866
4 changed files with 46 additions and 8 deletions
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2
src/Disks/AsynchronousReadIndirectBufferFromRemoteFS.h
View File

@ -24,6 +24,8 @@ namespace DB
* Buffers chain for diskWeb:
* AsynchronousIndirectReadBufferFromRemoteFS -> ReadBufferFromRemoteFS ->
* -> ReadIndirectBufferFromWebServer -> ReadBufferFromHttp -> ReadBufferFromIStream.
*
* We pass either `memory` or `prefetch_buffer` through all this chain and return it back.
*/
class AsynchronousReadIndirectBufferFromRemoteFS : public ReadBufferFromFileBase
{

25
src/Disks/ReadIndirectBufferFromWebServer.cpp
View File

@ -71,19 +71,30 @@ bool ReadIndirectBufferFromWebServer::nextImpl()
if (impl)
{
if (!use_external_buffer)
{
impl->position() = position();
assert(!impl->hasPendingData());
}
}
if (use_external_buffer)
{
/**
* use_external_buffer -- means we read into the buffer which
* was passed to us from somewhere else. We do not check whether
* previously returned buffer was read or not, because this branch
* means we are prefetching data, each nextImpl() call we can fill
* a different buffer.
*/
impl->set(internal_buffer.begin(), internal_buffer.size());
assert(working_buffer.begin() != nullptr);
assert(!internal_buffer.empty());
}
else
{
/**
* impl was initialized before, pass position() to it to make
* sure there is no pending data which was not read, becuase
* this branch means we read sequentially.
*/
impl->position() = position();
assert(!impl->hasPendingData());
}
}
WriteBufferFromOwnString error_msg;
for (size_t i = 0; (i < max_tries) && !successful_read && !next_result; ++i)

13
src/IO/ReadBufferFromS3.cpp
View File

@ -52,6 +52,13 @@ bool ReadBufferFromS3::nextImpl()
{
if (!use_external_buffer)
{
/**
* use_external_buffer -- means we read into the buffer which
* was passed to us from somewhere else. We do not check whether
* previously returned buffer was read or not, because this branch
* means we are prefetching data, each nextImpl() call we can fill
* a different buffer.
*/
impl->position() = position();
assert(!impl->hasPendingData());
}
@ -65,6 +72,12 @@ bool ReadBufferFromS3::nextImpl()
if (use_external_buffer)
{
/**
* use_external_buffer -- means we read into the buffer which
* was passed to us from somewhere else. We do not check whether
* previously returned buffer was read or not, because this branch
* means we are prefetching data.
*/
impl->set(internal_buffer.begin(), internal_buffer.size());
assert(working_buffer.begin() != nullptr);
assert(!internal_buffer.empty());

12
src/IO/ReadWriteBufferFromHTTP.h
View File

@ -213,12 +213,24 @@ namespace detail
if (use_external_buffer)
{
/**
* use_external_buffer -- means we read into the buffer which
* was passed to us from somewhere else. We do not check whether
* previously returned buffer was read or not, because this branch
* means we are prefetching data, each nextImpl() call we can fill
* a different buffer.
*/
impl->set(internal_buffer.begin(), internal_buffer.size());
assert(working_buffer.begin() != nullptr);
assert(!internal_buffer.empty());
}
else
{
/**
* impl was initialized before, pass position() to it to make
* sure there is no pending data which was not read, becuase
* this branch means we read sequentially.
*/
if (!working_buffer.empty())
impl->position() = position();
}