masaori335 commented on code in PR #13475:
URL: https://github.com/apache/trafficserver/pull/13475#discussion_r3732752205
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plugins/slice/server.cc:
##########
@@ -499,12 +502,174 @@ handleNextServerHeader(Data *const data)
return true;
}
+// Take the largest extent any block reports: blocks disagree when the origin
+// object was replaced in place, and the shorter one would leave a tail cached.
+void
+note_purge_extent(Data *const data, int64_t const length)
+{
+ if (length <= data->m_contentlen) {
+ return;
+ }
+
+ data->m_contentlen = length;
+ DEBUG_LOG("purge extent now %" PRId64 ", walking through block %" PRId64,
length,
+ data->purge_range().lastBlockFor(data->m_config->m_blockbytes));
+}
+
+// Record what the block response said, without answering the client.
+void
+note_purge_block_result(Data *const data)
+{
+ HttpHeader const header(data->m_resp_hdrmgr.m_buffer,
data->m_resp_hdrmgr.m_lochdr);
+ DEBUG_LOG("Purge block header\n%s", header.toString().c_str());
+
+ TSHttpStatus const status = header.status();
+
+ if (TS_HTTP_STATUS_OK == status) {
+ ++data->m_purge_hits;
+ data->m_purge_misses = 0;
+
+ // Not Content-Range: cache_range_requests reads that on a 200 as a stored
206
+ // and rewrites the status
+ ContentRange const purgedcr = content_range_for_key(header,
PURGED_CONTENT_RANGE.data(), PURGED_CONTENT_RANGE.size());
+ if (purgedcr.isValid() && 0 < purgedcr.m_length) {
+ note_purge_extent(data, purgedcr.m_length);
+ } else {
+ DEBUG_LOG("Purged block %" PRId64 " reported no usable extent",
data->m_blocknum);
+ }
+ } else {
+ // Already absent. The walk used to stop here, leaving every later block
cached.
+ ++data->m_purge_misses;
+ DEBUG_LOG("Purge block %" PRId64 " was not cached (%d)", data->m_blocknum,
status);
+ }
+}
+
+// Issue the next purge, or answer the client if the walk is over.
+void
+advance_purge(TSCont const contp, Data *const data)
+{
+ int64_t const blockbytes = data->m_config->m_blockbytes;
+ Range const range = data->purge_range();
+
+ ++data->m_blocknum;
+ int64_t const firstblock = range.firstBlockFor(blockbytes);
+ if (data->m_blocknum < firstblock) {
+ data->m_blocknum = firstblock;
+ }
+
+ // The requested range bounds the walk whether or not the extent is known yet
+ if (!range.blockIsInside(blockbytes, data->m_blocknum)) {
+ finish_purge(contp, data);
+ return;
+ }
+
+ // An open ended range has no such bound until some block reports an extent
+ if (data->m_contentlen < 0 && data->m_purge_miss_bound <=
data->m_purge_misses) {
+ DEBUG_LOG("purge gave up after %d consecutive uncached block(s)",
data->m_purge_misses);
+ finish_purge(contp, data);
+ return;
+ }
+
+ data->m_blockstate = BlockState::Pending;
+ if (!request_block(contp, data)) {
+ ERROR_LOG("Failed to issue purge for block %" PRId64, data->m_blocknum);
+ finish_purge(contp, data);
+ }
+}
+
} // namespace
+// Answer the client once every block has been walked. Nothing is written
+// downstream before this, so one uncached block cannot leak a 404 to the
client.
+// A non-NONE status overrides the outcome of the walk.
+void
+finish_purge(TSCont const contp, Data *const data, TSHttpStatus const status)
+{
+ data->m_upstream.close();
+ data->m_blockstate = BlockState::Done;
+
+ TSHttpStatus const reply =
+ (TS_HTTP_STATUS_NONE != status) ? status : (0 < data->m_purge_hits ?
TS_HTTP_STATUS_OK : TS_HTTP_STATUS_NOT_FOUND);
Review Comment:
I changed to stop walking at error.
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