120 lines
5.0 KiB
Diff
120 lines
5.0 KiB
Diff
From af18cb04f07555f49daef982c8c21459bfbe388c Mon Sep 17 00:00:00 2001
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From: Alex Rousskov <rousskov@measurement-factory.com>
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Date: Thu, 23 Nov 2023 18:27:24 +0000
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Subject: [PATCH 3/7] Bug 5309: frequent "lowestOffset () <= target_offset"
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assertion (#1561)
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Recent commit 122a6e3 left store_client::readOffset() unchanged but
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should have adjusted it to match changed copyInto.offset semantics:
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Starting with that commit, storeClientCopy() callers supply HTTP
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response _body_ offset rather than HTTP response offset.
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....
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This bug decreased readOffset() values (by the size of stored HTTP
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response headers), effectively telling Store that we are not yet done
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with some of the MemObject/mem_hdr bytes. This bug could cause slightly
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higher transaction memory usage because the same response bytes are
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trimmed later. This bug should not have caused any assertions.
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....
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However, the old mem_hdr::freeDataUpto() code that uses readOffset() is
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also broken -- the assertion in that method only "works" when
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readOffset() returns values matching a memory node boundary. The smaller
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values returned by buggy readOffset() triggered buggy assertions.
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....
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This minimal fix removes the recent store_client::readOffset() bug
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described above. We will address old mem_hdr problems separately.
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Modified-by: Alex Burmashev <alexander.burmashev@oracle.com>
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Signed-off-by: Alex Burmashev <alexander.burmashev@oracle.com>
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---
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src/MemObject.cc | 2 +-
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src/StoreClient.h | 19 ++++++++++---------
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src/store_client.cc | 13 +++++++++++++
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3 files changed, 24 insertions(+), 10 deletions(-)
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diff --git a/src/MemObject.cc b/src/MemObject.cc
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index d7aaf5e..650d3fd 100644
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--- a/src/MemObject.cc
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+++ b/src/MemObject.cc
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@@ -197,7 +197,7 @@ struct LowestMemReader : public unary_function<store_client, void> {
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void operator() (store_client const &x) {
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if (x.getType() == STORE_MEM_CLIENT)
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- current = std::min(current, x.readOffset());
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+ current = std::min(current, x.discardableHttpEnd());
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}
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int64_t current;
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diff --git a/src/StoreClient.h b/src/StoreClient.h
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index 1d90e5a..0524776 100644
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--- a/src/StoreClient.h
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+++ b/src/StoreClient.h
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@@ -54,15 +54,8 @@ public:
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store_client(StoreEntry *);
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~store_client();
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- /// An offset into the stored response bytes, including the HTTP response
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- /// headers (if any). Note that this offset does not include Store entry
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- /// metadata, because it is not a part of the stored response.
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- /// \retval 0 means the client wants to read HTTP response headers.
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- /// \retval +N the response byte that the client wants to read next.
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- /// \retval -N should not occur.
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- // TODO: Callers do not expect negative offset. Verify that the return
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- // value cannot be negative and convert to unsigned in this case.
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- int64_t readOffset() const { return copyInto.offset; }
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+ /// the client will not use HTTP response bytes with lower offsets (if any)
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+ auto discardableHttpEnd() const { return discardableHttpEnd_; }
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int getType() const;
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@@ -156,8 +149,16 @@ private:
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/// Storage and metadata associated with the current copy() request. Ought
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/// to be ignored when not answering a copy() request.
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+ /// * copyInto.offset is the requested HTTP response body offset;
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+ /// * copyInto.data is the client-owned, client-provided result buffer;
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+ /// * copyInto.length is the size of the .data result buffer;
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+ /// * copyInto.flags are unused by this class.
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StoreIOBuffer copyInto;
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+ // TODO: Convert to uint64_t after fixing mem_hdr::endOffset() and friends.
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+ /// \copydoc discardableHttpEnd()
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+ int64_t discardableHttpEnd_ = 0;
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+
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/// the total number of finishCallback() calls
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uint64_t answers;
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diff --git a/src/store_client.cc b/src/store_client.cc
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index 1731c4c..383aac8 100644
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--- a/src/store_client.cc
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+++ b/src/store_client.cc
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@@ -122,6 +122,16 @@ store_client::finishCallback()
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result = parsingBuffer->packBack();
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result.flags.error = object_ok ? 0 : 1;
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+ // TODO: Move object_ok handling above into this `if` statement.
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+ if (object_ok) {
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+ // works for zero hdr_sz cases as well; see also: nextHttpReadOffset()
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+ discardableHttpEnd_ = NaturalSum<int64_t>(entry->mem().baseReply().hdr_sz, result.offset, result.length).value();
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+ } else {
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+ // object_ok is sticky, so we will not be able to use any response bytes
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+ discardableHttpEnd_ = entry->mem().endOffset();
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+ }
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+ debugs(90, 7, "with " << result << "; discardableHttpEnd_=" << discardableHttpEnd_);
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+
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// no HTTP headers and no body bytes (but not because there was no space)
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atEof_ = !sendingHttpHeaders() && !result.length && copyInto.length;
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@@ -220,6 +230,9 @@ store_client::copy(StoreEntry * anEntry,
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parsingBuffer.emplace(copyInto);
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+ discardableHttpEnd_ = nextHttpReadOffset();
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+ debugs(90, 7, "discardableHttpEnd_=" << discardableHttpEnd_);
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+
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static bool copying (false);
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assert (!copying);
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copying = true;
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--
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2.39.3
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