[fix](filecache) add check and exception handle for empty block file

[freemandealer]

current code didn't check and handle cases when block file is fail to download (empty file). add check and handler for that.

What problem does this PR solve?

Issue Number: close #xxx

Related PR: #xxx

Problem Summary:

Release note

None

Check List (For Author)

• Test

  • Regression test
  • Unit Test
  • Manual test (add detailed scripts or steps below)
  • No need to test or manual test. Explain why:
    • This is a refactor/code format and no logic has been changed.
    • Previous test can cover this change.
    • No code files have been changed.
    • Other reason

• Behavior changed:

  • No.
  • Yes.

• Does this need documentation?

  • No.
  • Yes.

Check List (For Reviewer who merge this PR)

• Confirm the release note
• Confirm test cases
• Confirm document
• Add branch pick label

[Thearas]

Thank you for your contribution to Apache Doris.
Don't know what should be done next? See How to process your PR.

Please clearly describe your PR:

1. What problem was fixed (it's best to include specific error reporting information). How it was fixed.
2. Which behaviors were modified. What was the previous behavior, what is it now, why was it modified, and what possible impacts might there be.
3. What features were added. Why was this function added?
4. Which code was refactored and why was this part of the code refactored?
5. Which functions were optimized and what is the difference before and after the optimization?

[freemandealer]

run buildall

[hello-stephen]

BE UT Coverage Report

Increment line coverage 100.00% (15/15) 🎉

Increment coverage report
Complete coverage report

Category	Coverage
Function Coverage	53.10% (18976/35739)
Line Coverage	39.12% (175786/449321)
Region Coverage	33.65% (136061/404321)
Branch Coverage	34.65% (58766/169585)

[hello-stephen]

BE Regression && UT Coverage Report

Increment line coverage 100.00% (15/15) 🎉

Increment coverage report
Complete coverage report

Category	Coverage
Function Coverage	65.92% (23033/34939)
Line Coverage	52.79% (236539/448105)
Region Coverage	48.16% (196711/408444)
Branch Coverage	49.03% (83426/170138)

[freemandealer]

run buildall

[doris-robot]

TPC-H: Total hot run time: 32236 ms

machine: 'aliyun_ecs.c7a.8xlarge_32C64G'
scripts: https://github.com/apache/doris/tree/master/tools/tpch-tools
Tpch sf100 test result on commit 39db6814988046431abf9fca04b4fa7739491f0c, data reload: false

------ Round 1 ----------------------------------
q1	17634	4211	4076	4076
q2	2039	365	268	268
q3	10105	1277	726	726
q4	10205	823	328	328
q5	7753	2156	1943	1943
q6	237	183	144	144
q7	968	799	673	673
q8	9276	1462	1233	1233
q9	5008	4611	4635	4611
q10	6867	1844	1419	1419
q11	516	298	293	293
q12	733	752	611	611
q13	17825	3921	3173	3173
q14	293	291	274	274
q15	587	509	502	502
q16	746	692	626	626
q17	678	843	561	561
q18	6545	6502	6462	6462
q19	1189	966	639	639
q20	407	374	256	256
q21	3157	2515	2443	2443
q22	1027	1024	975	975
Total cold run time: 103795 ms
Total hot run time: 32236 ms

----- Round 2, with runtime_filter_mode=off -----
q1	4143	4064	4070	4064
q2	329	389	325	325
q3	2092	2614	2176	2176
q4	1398	1806	1326	1326
q5	4093	4008	4105	4008
q6	209	170	135	135
q7	1947	1793	2125	1793
q8	2614	2496	2446	2446
q9	7244	7177	7141	7141
q10	2637	2656	2349	2349
q11	569	489	461	461
q12	734	776	635	635
q13	3734	4056	3337	3337
q14	354	321	278	278
q15	540	512	502	502
q16	650	679	731	679
q17	1182	1414	1412	1412
q18	8111	7915	7836	7836
q19	959	887	898	887
q20	1986	2087	1983	1983
q21	4834	4482	4116	4116
q22	1072	1033	955	955
Total cold run time: 51431 ms
Total hot run time: 48844 ms

[doris-robot]

TPC-DS: Total hot run time: 172884 ms

machine: 'aliyun_ecs.c7a.8xlarge_32C64G'
scripts: https://github.com/apache/doris/tree/master/tools/tpcds-tools
TPC-DS sf100 test result on commit 39db6814988046431abf9fca04b4fa7739491f0c, data reload: false

query5	4362	584	417	417
query6	341	233	230	230
query7	4224	488	283	283
query8	343	257	253	253
query9	8774	2673	2650	2650
query10	507	367	329	329
query11	15241	15114	14815	14815
query12	176	121	116	116
query13	1271	497	380	380
query14	6076	3001	2835	2835
query14_1	2707	2690	2723	2690
query15	205	195	179	179
query16	995	486	460	460
query17	1107	734	544	544
query18	2451	427	331	331
query19	229	221	184	184
query20	120	116	114	114
query21	209	136	119	119
query22	4026	3910	3907	3907
query23	15959	15343	15343	15343
query23_1	15439	15459	15409	15409
query24	7401	1558	1177	1177
query24_1	1203	1180	1187	1180
query25	524	441	397	397
query26	1254	258	152	152
query27	2764	436	298	298
query28	4535	2139	2123	2123
query29	761	592	469	469
query30	311	241	212	212
query31	731	626	557	557
query32	81	70	69	69
query33	563	330	290	290
query34	913	890	534	534
query35	707	751	669	669
query36	878	889	789	789
query37	123	90	76	76
query38	2688	2708	2658	2658
query39	780	753	752	752
query39_1	700	709	707	707
query40	216	130	115	115
query41	64	64	64	64
query42	109	103	104	103
query43	482	460	407	407
query44	1363	727	722	722
query45	186	184	174	174
query46	867	953	610	610
query47	1421	1457	1298	1298
query48	304	328	239	239
query49	623	411	324	324
query50	652	289	209	209
query51	3801	3772	3785	3772
query52	104	108	98	98
query53	298	325	273	273
query54	279	264	244	244
query55	82	76	70	70
query56	285	291	291	291
query57	1001	1002	860	860
query58	257	249	245	245
query59	2178	2196	2007	2007
query60	317	317	297	297
query61	159	157	163	157
query62	404	361	323	323
query63	313	271	295	271
query64	4861	1299	972	972
query65	3825	3741	3754	3741
query66	1447	428	313	313
query67	14687	14690	15609	14690
query68	2796	1033	730	730
query69	453	356	317	317
query70	1021	942	913	913
query71	319	308	273	273
query72	5736	3545	3716	3545
query73	593	732	315	315
query74	8832	8847	8591	8591
query75	2760	2830	2466	2466
query76	2853	1070	680	680
query77	366	407	295	295
query78	9782	9773	9137	9137
query79	1101	936	584	584
query80	1324	617	519	519
query81	563	270	231	231
query82	1014	150	119	119
query83	407	279	259	259
query84	267	123	108	108
query85	1017	521	450	450
query86	424	322	319	319
query87	2858	2851	2802	2802
query88	3250	2220	2208	2208
query89	400	353	338	338
query90	1942	164	152	152
query91	171	159	144	144
query92	73	71	63	63
query93	985	931	532	532
query94	635	269	279	269
query95	572	336	308	308
query96	583	480	212	212
query97	2366	2355	2293	2293
query98	217	202	201	201
query99	595	564	526	526
Total cold run time: 247763 ms
Total hot run time: 172884 ms

[doris-robot]

ClickBench: Total hot run time: 26.85 s

machine: 'aliyun_ecs.c7a.8xlarge_32C64G'
scripts: https://github.com/apache/doris/tree/master/tools/clickbench-tools
ClickBench test result on commit 39db6814988046431abf9fca04b4fa7739491f0c, data reload: false

query1	0.06	0.04	0.05
query2	0.10	0.05	0.04
query3	0.26	0.09	0.09
query4	1.61	0.12	0.12
query5	0.28	0.25	0.24
query6	1.15	0.67	0.65
query7	0.04	0.02	0.03
query8	0.06	0.05	0.04
query9	0.57	0.48	0.50
query10	0.56	0.56	0.53
query11	0.15	0.10	0.10
query12	0.14	0.12	0.11
query13	0.60	0.57	0.59
query14	0.96	0.93	0.96
query15	0.79	0.78	0.78
query16	0.41	0.40	0.40
query17	1.03	1.10	0.99
query18	0.25	0.22	0.22
query19	1.94	1.88	1.87
query20	0.01	0.02	0.01
query21	15.44	0.29	0.15
query22	5.06	0.05	0.04
query23	15.85	0.29	0.11
query24	1.85	0.33	0.22
query25	0.08	0.08	0.07
query26	0.14	0.14	0.13
query27	0.05	0.06	0.05
query28	3.30	1.06	0.89
query29	12.64	3.95	3.17
query30	0.27	0.14	0.13
query31	2.82	0.66	0.41
query32	3.23	0.58	0.46
query33	3.05	3.01	3.13
query34	16.78	5.15	4.47
query35	4.51	4.47	4.49
query36	0.65	0.50	0.49
query37	0.11	0.07	0.06
query38	0.07	0.05	0.04
query39	0.05	0.03	0.03
query40	0.16	0.13	0.13
query41	0.09	0.04	0.03
query42	0.05	0.03	0.03
query43	0.04	0.04	0.03
Total cold run time: 97.26 s
Total hot run time: 26.85 s

[doris-robot]

BE UT Coverage Report

Increment line coverage 100.00% (15/15) 🎉

Increment coverage report
Complete coverage report

Category	Coverage
Function Coverage	53.12% (18991/35754)
Line Coverage	39.13% (175867/449477)
Region Coverage	33.69% (136243/404455)
Branch Coverage	34.66% (58800/169643)

[hello-stephen]

BE Regression && UT Coverage Report

Increment line coverage 100.00% (15/15) 🎉

Increment coverage report
Complete coverage report

Category	Coverage
Function Coverage	72.27% (25261/34954)
Line Coverage	59.42% (266355/448258)
Region Coverage	54.07% (220914/408574)
Branch Coverage	55.81% (94976/170192)

[dataroaring]

run buildall

[doris-robot]

TPC-H: Total hot run time: 31606 ms

machine: 'aliyun_ecs.c7a.8xlarge_32C64G'
scripts: https://github.com/apache/doris/tree/master/tools/tpch-tools
Tpch sf100 test result on commit b3c82cbba88237ebb4a434e0bff973a8b6847605, data reload: false

------ Round 1 ----------------------------------
q1	17650	4225	4053	4053
q2	2072	356	257	257
q3	10145	1290	738	738
q4	10203	885	314	314
q5	7538	2045	1942	1942
q6	222	177	141	141
q7	939	786	655	655
q8	9279	1385	1154	1154
q9	4862	4624	4559	4559
q10	6811	1842	1414	1414
q11	522	310	276	276
q12	716	725	589	589
q13	17788	3840	3049	3049
q14	293	305	272	272
q15	609	504	516	504
q16	715	688	619	619
q17	679	851	479	479
q18	6666	6464	6502	6464
q19	1107	972	608	608
q20	403	360	245	245
q21	3081	2478	2300	2300
q22	1049	1018	974	974
Total cold run time: 103349 ms
Total hot run time: 31606 ms

----- Round 2, with runtime_filter_mode=off -----
q1	4112	4048	4025	4025
q2	325	408	315	315
q3	2091	2594	2199	2199
q4	1335	1747	1389	1389
q5	4099	4003	4014	4003
q6	208	170	131	131
q7	1892	1773	1625	1625
q8	2821	2509	2473	2473
q9	7241	7103	7171	7103
q10	2393	2773	2351	2351
q11	538	504	485	485
q12	727	770	633	633
q13	3729	4032	3388	3388
q14	298	300	301	300
q15	560	505	495	495
q16	634	670	642	642
q17	1154	1346	1407	1346
q18	8141	8076	7574	7574
q19	934	885	890	885
q20	2039	2095	1922	1922
q21	4727	4475	4281	4281
q22	1086	1025	981	981
Total cold run time: 51084 ms
Total hot run time: 48546 ms

[doris-robot]

TPC-DS: Total hot run time: 172975 ms

machine: 'aliyun_ecs.c7a.8xlarge_32C64G'
scripts: https://github.com/apache/doris/tree/master/tools/tpcds-tools
TPC-DS sf100 test result on commit b3c82cbba88237ebb4a434e0bff973a8b6847605, data reload: false

query5	4581	577	430	430
query6	339	214	206	206
query7	4231	456	263	263
query8	340	249	227	227
query9	8768	2661	2635	2635
query10	494	369	314	314
query11	15358	15196	14868	14868
query12	173	116	116	116
query13	1252	471	359	359
query14	6224	2990	2748	2748
query14_1	2649	2637	2658	2637
query15	202	190	177	177
query16	1003	464	449	449
query17	1105	701	575	575
query18	2489	443	346	346
query19	234	230	205	205
query20	119	116	114	114
query21	218	141	121	121
query22	3901	3854	4018	3854
query23	15955	15619	15331	15331
query23_1	15475	15430	15427	15427
query24	7259	1555	1172	1172
query24_1	1187	1196	1208	1196
query25	573	476	424	424
query26	833	266	166	166
query27	2741	450	289	289
query28	4439	2134	2126	2126
query29	832	561	457	457
query30	319	239	215	215
query31	746	648	551	551
query32	76	70	79	70
query33	560	346	292	292
query34	895	895	538	538
query35	747	750	672	672
query36	877	889	903	889
query37	119	94	73	73
query38	2740	2653	2744	2653
query39	797	744	730	730
query39_1	711	708	717	708
query40	210	134	122	122
query41	64	61	62	61
query42	104	102	99	99
query43	464	478	434	434
query44	1303	720	716	716
query45	187	184	178	178
query46	836	949	592	592
query47	1371	1416	1349	1349
query48	308	332	235	235
query49	616	428	315	315
query50	630	278	207	207
query51	3821	3768	3766	3766
query52	102	105	106	105
query53	306	329	267	267
query54	282	254	253	253
query55	82	73	70	70
query56	277	291	274	274
query57	1003	1038	960	960
query58	264	250	245	245
query59	2179	2230	2039	2039
query60	312	305	290	290
query61	168	153	152	152
query62	403	348	333	333
query63	297	266	277	266
query64	4008	1309	975	975
query65	3799	3738	3753	3738
query66	1396	414	295	295
query67	14920	15749	15448	15448
query68	8232	981	693	693
query69	491	344	303	303
query70	1070	924	969	924
query71	367	301	273	273
query72	5779	3443	3502	3443
query73	769	718	299	299
query74	8807	8746	8613	8613
query75	2884	2809	2424	2424
query76	3906	1062	628	628
query77	582	369	271	271
query78	9739	9879	9178	9178
query79	1238	924	582	582
query80	608	586	477	477
query81	540	260	231	231
query82	207	144	111	111
query83	255	255	231	231
query84	264	117	103	103
query85	904	516	455	455
query86	396	311	289	289
query87	2890	2860	2767	2767
query88	3121	2222	2229	2222
query89	384	357	319	319
query90	2249	152	145	145
query91	168	158	144	144
query92	84	70	64	64
query93	1698	907	531	531
query94	565	320	309	309
query95	579	317	296	296
query96	567	456	206	206
query97	2329	2401	2297	2297
query98	215	205	205	205
query99	591	575	516	516
Total cold run time: 253091 ms
Total hot run time: 172975 ms

[dataroaring]

LGTM

[github-actions]

PR approved by at least one committer and no changes requested.

[github-actions]

PR approved by anyone and no changes requested.

[freemandealer]

run p0

[dataroaring]

Code Review: fix add check and exception handle for empty block file

Summary

This PR adds defensive handling for cases where a file cache block has zero downloaded bytes but attempts to transition to DOWNLOADED state. This could happen when a download fails silently or is interrupted.

Analysis

Changes in file_block.cpp

1. set_downloaded() - Early exit for empty blocks:

if (_downloaded_size == 0) {
    _download_state = State::EMPTY;
    _downloader_id = 0;
    return Status::InternalError("Try to set empty block {} as downloaded",
                                 _block_range.to_string());
}

2. finalize() - Handle zero-byte finalization:

if (_downloaded_size == 0) {
    std::lock_guard block_lock(_mutex);
    _download_state = State::EMPTY;
    _downloader_id = 0;
    _cv.notify_all();  // Wake up waiters
    return Status::InternalError("Try to finalize an empty file block {}",
                                 _block_range.to_string());
}

Positive Aspects

1. Proper State Transition: Sets state to EMPTY and clears _downloader_id, allowing the block to be re-acquired
2. Notifies Waiters: Calls _cv.notify_all() so other threads waiting for this block don't deadlock
3. Good Test Coverage: Includes 3 test cases covering:
   • finalize_empty_block - finalize without any data
   • finalize_partial_block - finalize with partial data (verifies shrinking works)
   • set_downloaded_empty_block_branch - direct test of the early exit

Potential Issue

In finalize(), the condition check order changed:

Before:

if (_downloaded_size != 0 && _downloaded_size != _block_range.size()) {

After:

if (_downloaded_size == 0) { /* error */ }
if (_downloaded_size != _block_range.size()) { /* shrink */ }

This is semantically equivalent but now the shrinking logic will also run when _downloaded_size == _block_range.size() (though it's a no-op in that case). This is fine but slightly less efficient.

Question

The EMPTY state is used for both:

1. Initial state (block not yet downloaded)
2. Error state (download failed with zero bytes)

Is there value in distinguishing these with a separate FAILED state? This would allow cleaner error handling and potentially different retry policies.

Verdict

LGTM - Good defensive fix with proper test coverage. The changes correctly handle the edge case of empty block finalization while maintaining proper synchronization semantics.

Approved for merge.