Share TermsEnum if possible while applying DV updates [LUCENE-8602]

[asfimport]

Today we pull a new terms enum when we apply DV updates even though the
field stays the same which is the common case. Benchmarking this on a
larger term dictionary with a significant number of updates shows a
2x improvement in performance.

---

Migrated from LUCENE-8602 by Simon Willnauer (@s1monw), resolved Dec 11 2018
Pull requests: apache/lucene-solr#523

[asfimport]

ASF subversion and git services (migrated from JIRA)

Commit d08e2d4 in lucene-solr's branch refs/heads/master from @s1monw
https://git-wip-us.apache.org/repos/asf?p=lucene-solr.git;h=d08e2d4

LUCENE-8602: Share TermsEnum if possible while applying DV updates

Today we pull a new terms enum when we apply DV updates even though the
field stays the same which is the common case. Benchmarking this on a
larger term dictionary with a significant number of updates shows a
2x improvement in performance.

[asfimport]

ASF subversion and git services (migrated from JIRA)

Commit 01ad36d in lucene-solr's branch refs/heads/branch_7x from @s1monw
https://git-wip-us.apache.org/repos/asf?p=lucene-solr.git;h=01ad36d

LUCENE-8602: Share TermsEnum if possible while applying DV updates

Today we pull a new terms enum when we apply DV updates even though the
field stays the same which is the common case. Benchmarking this on a
larger term dictionary with a significant number of updates shows a
2x improvement in performance.

[asfimport]

ASF subversion and git services (migrated from JIRA)

Commit d08e2d4 in lucene-solr's branch refs/heads/jira/http2 from @s1monw
https://git-wip-us.apache.org/repos/asf?p=lucene-solr.git;h=d08e2d4

LUCENE-8602: Share TermsEnum if possible while applying DV updates

Today we pull a new terms enum when we apply DV updates even though the
field stays the same which is the common case. Benchmarking this on a
larger term dictionary with a significant number of updates shows a
2x improvement in performance.

[asfimport]

ASF subversion and git services (migrated from JIRA)

Commit 4272c63 in lucene-solr's branch refs/heads/master from @s1monw
https://git-wip-us.apache.org/repos/asf?p=lucene-solr.git;h=4272c63

#9654: Extract utility class to iterate over terms docs

Today we re-implement the same algorithm in various places
when we want to consume all docs for a set/list of terms. This
caused serious slowdowns for instance in the case of applying
updates fixed in LUCENE-8602. This change extracts the common
usage and shares the interation code including logic to reuse
Terms and PostingsEnum instances as much as possble and adds
tests for it.

[asfimport]

ASF subversion and git services (migrated from JIRA)

Commit 8f4e4a4 in lucene-solr's branch refs/heads/branch_7x from @s1monw
https://git-wip-us.apache.org/repos/asf?p=lucene-solr.git;h=8f4e4a4

#9654: Extract utility class to iterate over terms docs

Today we re-implement the same algorithm in various places
when we want to consume all docs for a set/list of terms. This
caused serious slowdowns for instance in the case of applying
updates fixed in LUCENE-8602. This change extracts the common
usage and shares the interation code including logic to reuse
Terms and PostingsEnum instances as much as possble and adds
tests for it.