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Find the next table at epoch
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lib/xks/manifest.ex
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lib/xks/manifest.ex
···
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# so we set the prev_tombstone? flag to cancel out the next entry
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do_seek_table(manifest, epoch, level, seek_key, key, true)
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{{^level, sk_key, sk_ver, _ep}, [{_key, value}]} ->
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{{^level, sk_key, sk_ver, _ep} = key, [{_key, value}]} ->
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# This entry is visible and may contain `seek_key`
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{ek_key, ek_ver, lb_index, lb_checksum, _id} = value
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{ek_key, ek_ver, _lb_index, _lb_checksum, _id} = value
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# This invariant is guaranteed because we are calling prev(seek_key + 1) to get here
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assert {sk_key, sk_ver} <= seek_key
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case seek_key < {ek_key, ek_ver} do
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true ->
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# If seek_key < end_key, this table contains `seek_key`
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table = {:table, lb_index, lb_checksum, {sk_key, sk_ver}, {ek_key, ek_ver}}
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{:ok, table}
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{:ok, table_from_kv(key, value)}
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false ->
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# If seek_key >= end_key, that means there is a "hole" in the keyspace
···
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end
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_ ->
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# Hit the start of the level without finding a table
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:error
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end
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end
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@spec next_table(t, non_neg_integer, non_neg_integer, tuple) :: {:ok, tuple} | :error
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def next_table(manifest, epoch, level, {:table, _i, _ck, _start_key, _end_key, table_key} = _table) do
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do_next_table(manifest, epoch, level, table_key)
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end
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defp do_next_table(manifest, epoch, level, prev_key) do
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case :ets.next_lookup(manifest, prev_key) do
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{{^level, _k, _ver, ep} = key, _obj} when ep > epoch ->
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# This entry is not visible at `epoch`
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do_next_table(manifest, epoch, level, key)
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{{^level, sk_key, sk_ver, _ep} = key, [{_key, value}]} ->
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case :ets.next_lookup(manifest, key) do
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{{^level, ^sk_key, ^sk_ver, _ep} = next_key, [{_key, :tombstone}]} ->
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# The entry was deleted, skip past the tombstone
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do_next_table(manifest, epoch, level, next_key)
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_ ->
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# The next entry is *not* a tombstone, so this entry is the next table visible at `epoch`
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{:ok, table_from_kv(key, value)}
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end
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_ ->
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# Hit the end of the level without finding a table
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:error
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end
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end
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defp table_from_kv(manifest_key, manifest_value) do
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{_level, sk_key, sk_ver, _epoch} = manifest_key
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{ek_key, ek_ver, lb_index, lb_checksum, _id} = manifest_value
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{:table, lb_index, lb_checksum, {sk_key, sk_ver}, {ek_key, ek_ver}, manifest_key}
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end
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@spec list_overlapping_tables(t, non_neg_integer, non_neg_integer, {binary, non_neg_integer}, {binary, non_neg_integer}) :: [tuple]
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lib/xks/xks.ex
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-1
lib/xks/xks.ex
···
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epoch = :atomics.get(xks.epoch_atomic, 1)
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Manifest.seek_table(manifest, epoch, 1, key, version)
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|> dbg()
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#|> dbg()
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#|> tap(fn result -> is_tuple(result) && dbg(Manifest.next_table(manifest, epoch, 1, elem(result, 1))) end)
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Manifest.list_memtables(xks.manifest, epoch)
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|> Enum.find_value(:error, fn {_id, memtable} ->