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reftable/merged: stop using generic tables in the merged table

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The merged table provides access to a reftable stack by merging the
contents of those tables into a virtual table. These subtables are being
tracked via `struct reftable_table`, which is a generic interface for
accessing either a single reftable or a merged reftable. So in theory,
it would be possible for the merged table to merge together other merged
tables.

This is somewhat nonsensical though: we only ever set up a merged table
over normal reftables, and there is no reason to do otherwise. This
generic interface thus makes the code way harder to follow and reason
about than really necessary. The abstraction layer may also have an
impact on performance, even though the extra set of vtable function
calls probably doesn't really matter.

Refactor the merged tables to use a `struct reftable_reader` for each of
the subtables instead, which gives us direct access to the underlying
tables. Adjust names accordingly.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Patrick Steinhardt
2024-08-22 08:34:44 +02:00
committed by Junio C Hamano
parent 6631ed3ce7
commit b8ca235ca5
8 changed files with 60 additions and 75 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
t/unit-tests/t-reftable-merged.c
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@ -94,10 +94,8 @@ merged_table_from_records(struct reftable_ref_record **refs,
struct strbuf *buf, const size_t n)
{
struct reftable_merged_table *mt = NULL;
struct reftable_table *tabs;
int err;
REFTABLE_CALLOC_ARRAY(tabs, n);
REFTABLE_CALLOC_ARRAY(*readers, n);
REFTABLE_CALLOC_ARRAY(*source, n);
@ -108,10 +106,9 @@ merged_table_from_records(struct reftable_ref_record **refs,
err = reftable_new_reader(&(*readers)[i], &(*source)[i],
"name");
check(!err);
reftable_table_from_reader(&tabs[i], (*readers)[i]);
}
err = reftable_merged_table_new(&mt, tabs, n, GIT_SHA1_FORMAT_ID);
err = reftable_merged_table_new(&mt, *readers, n, GIT_SHA1_FORMAT_ID);
check(!err);
return mt;
}
@ -272,10 +269,8 @@ merged_table_from_log_records(struct reftable_log_record **logs,
struct strbuf *buf, const size_t n)
{
struct reftable_merged_table *mt = NULL;
struct reftable_table *tabs;
int err;
REFTABLE_CALLOC_ARRAY(tabs, n);
REFTABLE_CALLOC_ARRAY(*readers, n);
REFTABLE_CALLOC_ARRAY(*source, n);
@ -286,10 +281,9 @@ merged_table_from_log_records(struct reftable_log_record **logs,
err = reftable_new_reader(&(*readers)[i], &(*source)[i],
"name");
check(!err);
reftable_table_from_reader(&tabs[i], (*readers)[i]);
}
err = reftable_merged_table_new(&mt, tabs, n, GIT_SHA1_FORMAT_ID);
err = reftable_merged_table_new(&mt, *readers, n, GIT_SHA1_FORMAT_ID);
check(!err);
return mt;
}
@ -418,7 +412,6 @@ static void t_default_write_opts(void)
};
int err;
struct reftable_block_source source = { 0 };
struct reftable_table *tab = reftable_calloc(1, sizeof(*tab));
uint32_t hash_id;
struct reftable_reader *rd = NULL;
struct reftable_merged_table *merged = NULL;
@ -440,10 +433,9 @@ static void t_default_write_opts(void)
hash_id = reftable_reader_hash_id(rd);
check_int(hash_id, ==, GIT_SHA1_FORMAT_ID);
reftable_table_from_reader(&tab[0], rd);
err = reftable_merged_table_new(&merged, tab, 1, GIT_SHA256_FORMAT_ID);
err = reftable_merged_table_new(&merged, &rd, 1, GIT_SHA256_FORMAT_ID);
check_int(err, ==, REFTABLE_FORMAT_ERROR);
err = reftable_merged_table_new(&merged, tab, 1, GIT_SHA1_FORMAT_ID);
err = reftable_merged_table_new(&merged, &rd, 1, GIT_SHA1_FORMAT_ID);
check(!err);
reftable_reader_free(rd);