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Cleanup: memory cache lookup code #13060

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Cleanup: memory cache lookup code #13060

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62 changes: 38 additions & 24 deletions src/iocore/cache/CacheVC.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -69,6 +69,7 @@

namespace
{
DbgCtl dbg_ctl_cache_ram{"cache_ram"};
DbgCtl dbg_ctl_cache_bc{"cache_bc"};
DbgCtl dbg_ctl_cache_disk_error{"cache_disk_error"};
DbgCtl dbg_ctl_cache_read{"cache_read"};
Expand Down Expand Up @@ -449,27 +450,56 @@ CacheVC::handleReadDone(int event, Event * /* e ATS_UNUSED */)

int
CacheVC::handleRead(int /* event ATS_UNUSED */, Event * /* e ATS_UNUSED */)

{
cancel_trigger();

f.doc_from_ram_cache = false;

ink_assert(stripe->mutex->thread_holding == this_ethread());

// 1. check RAM cache
if (load_from_ram_cache()) {
goto LramHit;
} else if (load_from_last_open_read_call()) {
goto LmemHit;
} else if (load_from_aggregation_buffer()) {
Dbg(dbg_ctl_cache_ram, "RAM cache hit");
f.doc_from_ram_cache = true;
io.aio_result = io.aiocb.aio_nbytes;

Doc *doc = reinterpret_cast<Doc *>(buf->data());
if (cache_config_ram_cache_compress && doc->doc_type == CACHE_FRAG_TYPE_HTTP && doc->hlen) {
SET_HANDLER(&CacheVC::handleReadDone);
return EVENT_RETURN;
}

POP_HANDLER;
return EVENT_RETURN;
}

// 2. check last open read cache
if (load_from_last_open_read_call()) {
Dbg(dbg_ctl_cache_ram, "last open read hit");
f.doc_from_ram_cache = true;
io.aio_result = io.aiocb.aio_nbytes;

POP_HANDLER;
return EVENT_RETURN;
}

// 3. check aggregation buffer
if (load_from_aggregation_buffer()) {
Dbg(dbg_ctl_cache_ram, "aggregation buffer hit");
f.doc_from_ram_cache = true;
io.aio_result = io.aiocb.aio_nbytes;

SET_HANDLER(&CacheVC::handleReadDone);
return EVENT_RETURN;
}

// 4. read from Disk (AIO) due to all memory cache miss
Dbg(dbg_ctl_cache_ram, "all memory cache miss");

ts::Metrics::Counter::increment(cache_rsb.all_mem_misses);
ts::Metrics::Counter::increment(stripe->cache_vol->vol_rsb.all_mem_misses);

// enqueue AIO read
io.aiocb.aio_fildes = stripe->fd;
io.aiocb.aio_offset = stripe->vol_offset(&dir);
if (static_cast<off_t>(io.aiocb.aio_offset + io.aiocb.aio_nbytes) > static_cast<off_t>(stripe->skip + stripe->len)) {
Expand All @@ -480,30 +510,14 @@ CacheVC::handleRead(int /* event ATS_UNUSED */, Event * /* e ATS_UNUSED */)
io.action = this;
io.thread = mutex->thread_holding->tt == DEDICATED ? AIO_CALLBACK_THREAD_ANY : mutex->thread_holding;
SET_HANDLER(&CacheVC::handleReadDone);
ink_assert(ink_aio_read(&io) >= 0);

// ToDo: Why are these for debug only ??
#if DEBUG
int res = ink_aio_read(&io);
ink_assert(res >= 0);

ts::Metrics::Counter::increment(cache_rsb.pread_count);
ts::Metrics::Counter::increment(stripe->cache_vol->vol_rsb.pread_count);
#endif

return EVENT_CONT;

LramHit: {
f.doc_from_ram_cache = true;
io.aio_result = io.aiocb.aio_nbytes;
Doc *doc = reinterpret_cast<Doc *>(buf->data());
if (cache_config_ram_cache_compress && doc->doc_type == CACHE_FRAG_TYPE_HTTP && doc->hlen) {
SET_HANDLER(&CacheVC::handleReadDone);
return EVENT_RETURN;
}
}
LmemHit:
f.doc_from_ram_cache = true;
io.aio_result = io.aiocb.aio_nbytes;
POP_HANDLER;
return EVENT_RETURN; // allow the caller to release the volume lock
}

bool
Expand Down