On 6/25/2020 3:25 AM, René Scharfe wrote:
> Am 23.06.20 um 19:47 schrieb SZEDER Gábor via GitGitGadget:
>> From: =?UTF-8?q?SZEDER=20G=C3=A1bor?= <szeder.dev@xxxxxxxxx>
>>
>> In write_commit_graph_file() we now have one block of code filling the
>> array of 'struct chunk_info' with the IDs and sizes of chunks to be
>> written, and an other block of code calling the functions responsible
>> for writing individual chunks. In case of optional chunks like Extra
>> Edge List an Base Graphs List there is also a condition checking
>> whether that chunk is necessary/desired, and that same condition is
>> repeated in both blocks of code. Other, newer chunks have similar
>> optional conditions.
>>
>> Eliminate these repeated conditions by storing the function pointers
>> responsible for writing individual chunks in the 'struct chunk_info'
>> array as well, and calling them in a loop to write the commit-graph
>> file. This will open up the possibility for a bit of foolproofing in
>> the following patch.
>
> You can do that without storing function pointers by selecting the
> function to use based on the chunk ID -- like parse_commit_graph() does
> on the read side. Advantage: You don't need to press all write
> functions into the same mold and can keep their individual signatures.
I do think that the loop without a switch statement is valuable.
It focuses the updates for new chunks to be localized to the
section that calculates the offset values.
>>
>> Signed-off-by: SZEDER Gábor <szeder.dev@xxxxxxxxx>
>> Signed-off-by: Derrick Stolee <dstolee@xxxxxxxxxxxxx>
>> ---
>> commit-graph.c | 31 +++++++++++++++++++------------
>> 1 file changed, 19 insertions(+), 12 deletions(-)
>>
>> diff --git a/commit-graph.c b/commit-graph.c
>> index f33bfe49b3..086fc2d070 100644
>> --- a/commit-graph.c
>> +++ b/commit-graph.c
>> @@ -1555,9 +1555,13 @@ static int write_graph_chunk_base(struct hashfile *f,
>> return 0;
>> }
>>
>> +typedef int (*chunk_write_fn)(struct hashfile *f,
>> + struct write_commit_graph_context *ctx);
>> +
>> struct chunk_info {
>> uint32_t id;
>> uint64_t size;
>> + chunk_write_fn write_fn;
>> };
>>
>> static int write_commit_graph_file(struct write_commit_graph_context *ctx)
>> @@ -1615,27 +1619,34 @@ static int write_commit_graph_file(struct write_commit_graph_context *ctx)
>>
>> chunks[0].id = GRAPH_CHUNKID_OIDFANOUT;
>> chunks[0].size = GRAPH_FANOUT_SIZE;
>> + chunks[0].write_fn = write_graph_chunk_fanout;
>> chunks[1].id = GRAPH_CHUNKID_OIDLOOKUP;
>> chunks[1].size = hashsz * ctx->commits.nr;
>> + chunks[1].write_fn = write_graph_chunk_oids;
>> chunks[2].id = GRAPH_CHUNKID_DATA;
>> chunks[2].size = (hashsz + 16) * ctx->commits.nr;
>> + chunks[2].write_fn = write_graph_chunk_data;
>> if (ctx->num_extra_edges) {
>> chunks[num_chunks].id = GRAPH_CHUNKID_EXTRAEDGES;
>> chunks[num_chunks].size = 4 * ctx->num_extra_edges;
>> + chunks[num_chunks].write_fn = write_graph_chunk_extra_edges;
>> num_chunks++;
>> }
>> if (ctx->changed_paths) {
>> chunks[num_chunks].id = GRAPH_CHUNKID_BLOOMINDEXES;
>> chunks[num_chunks].size = sizeof(uint32_t) * ctx->commits.nr;
>> + chunks[num_chunks].write_fn = write_graph_chunk_bloom_indexes;
>> num_chunks++;
>> chunks[num_chunks].id = GRAPH_CHUNKID_BLOOMDATA;
>> chunks[num_chunks].size = sizeof(uint32_t) * 3
>> + ctx->total_bloom_filter_data_size;
>> + chunks[num_chunks].write_fn = write_graph_chunk_bloom_data;
>> num_chunks++;
>> }
>> if (ctx->num_commit_graphs_after > 1) {
>> chunks[num_chunks].id = GRAPH_CHUNKID_BASE;
>> chunks[num_chunks].size = hashsz * (ctx->num_commit_graphs_after - 1);
>> + chunks[num_chunks].write_fn = write_graph_chunk_base;
>> num_chunks++;
>> }
>>
>> @@ -1671,19 +1682,15 @@ static int write_commit_graph_file(struct write_commit_graph_context *ctx)
>> progress_title.buf,
>> num_chunks * ctx->commits.nr);
>> }
>> - write_graph_chunk_fanout(f, ctx);
>> - write_graph_chunk_oids(f, ctx);
>> - write_graph_chunk_data(f, ctx);
>> - if (ctx->num_extra_edges)
>> - write_graph_chunk_extra_edges(f, ctx);
>> - if (ctx->changed_paths) {
>> - write_graph_chunk_bloom_indexes(f, ctx);
>> - write_graph_chunk_bloom_data(f, ctx);
>> - }
>> - if (ctx->num_commit_graphs_after > 1 &&
>> - write_graph_chunk_base(f, ctx)) {
>> - return -1;
>> +
>> + for (i = 0; i < num_chunks; i++) {
>> + if (chunks[i].write_fn(f, ctx)) {
>> + error(_("failed writing chunk with id %"PRIx32""),
>> + chunks[i].id);
>
> Of all the write functions only write_graph_chunk_base() can return
> non-zero and it already prints an error message in that case ("failed to
> write correct number of base graph ids"). Why add this one?
Ok, we can require the chunk methods to write an error() message with
appropriate context and simply return -1 here.
Thanks,
-Stolee
