Unify DB and Handle types into just DB

[joamaki]

This removes the separate Handle type to allow decorating DB with the handle name in Hive:

       hive.Options{
               // Create a named DB handle for each module.
               ModuleDecorator: func(db *statedb.DB, id cell.ModuleID) *statedb.DB {
                       return db.NewHandle(string(id))
               },
       },

With this we can get StateDB metrics accounted by module, allowing us to for example seeing which module
has long-running WriteTxns etc.

[github-actions]

$ make test
go: downloading github.com/mitchellh/mapstructure v1.5.0
go: downloading golang.org/x/term v0.16.0
go: downloading github.com/spf13/cast v1.6.0
go: downloading github.com/fsnotify/fsnotify v1.7.0
go: downloading github.com/sagikazarmark/slog-shim v0.1.0
go: downloading github.com/spf13/afero v1.11.0
go: downloading golang.org/x/sys v0.17.0
go: downloading github.com/subosito/gotenv v1.6.0
go: downloading github.com/hashicorp/hcl v1.0.0
go: downloading gopkg.in/ini.v1 v1.67.0
go: downloading github.com/magiconair/properties v1.8.7
go: downloading github.com/pelletier/go-toml/v2 v2.1.0
go: downloading golang.org/x/text v0.14.0
	github.com/cilium/statedb/reconciler/benchmark		coverage: 0.0% of statements
	github.com/cilium/statedb/reconciler/example		coverage: 0.0% of statements
ok  	github.com/cilium/statedb	5.584s	coverage: 88.3% of statements
ok  	github.com/cilium/statedb/index	0.004s	coverage: 44.6% of statements
ok  	github.com/cilium/statedb/internal	0.007s	coverage: 93.3% of statements
ok  	github.com/cilium/statedb/part	2.549s	coverage: 82.8% of statements
ok  	github.com/cilium/statedb/reconciler	2.506s	coverage: 92.9% of statements
-----
$ make bench
go test ./... -bench . -benchmem -test.run xxx
goos: linux
goarch: amd64
pkg: github.com/cilium/statedb
cpu: AMD EPYC 7763 64-Core Processor                
BenchmarkDB_WriteTxn_1-4                    	  444542	      2578 ns/op	    387890 objects/sec	    2800 B/op	      32 allocs/op
BenchmarkDB_WriteTxn_10-4                   	 1244499	       983.8 ns/op	   1016502 objects/sec	     742 B/op	      10 allocs/op
BenchmarkDB_WriteTxn_100-4                  	 1585818	       757.2 ns/op	   1320717 objects/sec	     595 B/op	       7 allocs/op
BenchmarkDB_WriteTxn_1000-4                 	 1520791	       788.2 ns/op	   1268778 objects/sec	     550 B/op	       7 allocs/op
BenchmarkDB_WriteTxn_100_SecondaryIndex-4   	  504988	      2260 ns/op	    442385 objects/sec	    1489 B/op	      37 allocs/op
BenchmarkDB_Modify-4                        	    1344	    914203 ns/op	   1093850 objects/sec	  768756 B/op	    8457 allocs/op
BenchmarkDB_GetInsert-4                     	    1246	   1023935 ns/op	    976625 objects/sec	  752813 B/op	    8458 allocs/op
BenchmarkDB_RandomInsert-4                  	    2368	    496158 ns/op	   2015485 objects/sec	  402239 B/op	    7098 allocs/op
BenchmarkDB_RandomReplace-4                 	     330	   3670694 ns/op	    272428 objects/sec	 2344571 B/op	   48567 allocs/op
BenchmarkDB_SequentialInsert-4              	    1569	    792173 ns/op	   1262350 objects/sec	  551510 B/op	    7287 allocs/op
BenchmarkDB_Changes_Baseline-4              	    1266	    947001 ns/op	   1055966 objects/sec	  553176 B/op	   10253 allocs/op
BenchmarkDB_Changes-4                       	     691	   1685090 ns/op	    593440 objects/sec	  993102 B/op	   14493 allocs/op
BenchmarkDB_RandomLookup-4                  	   21475	     58606 ns/op	  17063066 objects/sec	     144 B/op	       1 allocs/op
BenchmarkDB_SequentialLookup-4              	   27534	     44645 ns/op	  22399064 objects/sec	       0 B/op	       0 allocs/op
BenchmarkDB_FullIteration_All-4             	     817	   1253307 ns/op	  79789072 objects/sec	     464 B/op	      12 allocs/op
BenchmarkDB_FullIteration_Get-4             	     224	   5291197 ns/op	  18899351 objects/sec	       0 B/op	       0 allocs/op
BenchmarkDB_PropagationDelay-4              	  507836	      2298 ns/op	        20.00 50th_µs	        23.00 90th_µs	        85.00 99th_µs	    1585 B/op	      24 allocs/op
PASS
ok  	github.com/cilium/statedb	26.559s
PASS
ok  	github.com/cilium/statedb/index	0.004s
PASS
ok  	github.com/cilium/statedb/internal	0.005s
goos: linux
goarch: amd64
pkg: github.com/cilium/statedb/part
cpu: AMD EPYC 7763 64-Core Processor                
Benchmark_Insert_RootOnlyWatch-4    	    8811	    131821 ns/op	   7586032 objects/sec	  104162 B/op	    2041 allocs/op
Benchmark_Insert-4                  	    6021	    185995 ns/op	   5376499 objects/sec	  219063 B/op	    3064 allocs/op
Benchmark_Modify-4                  	    8293	    141783 ns/op	   7053020 objects/sec	  212736 B/op	    1205 allocs/op
Benchmark_GetInsert-4               	    5884	    184698 ns/op	   5414263 objects/sec	  212267 B/op	    1204 allocs/op
Benchmark_Replace-4                 	27058000	        44.47 ns/op	  22486298 objects/sec	       0 B/op	       0 allocs/op
Benchmark_Replace_RootOnlyWatch-4   	27015212	        44.59 ns/op	  22426503 objects/sec	       0 B/op	       0 allocs/op
Benchmark_txn_1-4                   	 3012993	       399.7 ns/op	   2501786 objects/sec	     448 B/op	       7 allocs/op
Benchmark_txn_10-4                  	 7332902	       164.8 ns/op	   6066594 objects/sec	     154 B/op	       2 allocs/op
Benchmark_txn_100-4                 	 7945231	       150.3 ns/op	   6652305 objects/sec	     224 B/op	       2 allocs/op
Benchmark_txn_1000-4                	 7122537	       174.2 ns/op	   5741760 objects/sec	     216 B/op	       2 allocs/op
Benchmark_txn_delete_1-4            	 3108771	       382.3 ns/op	   2615625 objects/sec	     856 B/op	       6 allocs/op
Benchmark_txn_delete_10-4           	 8484058	       138.9 ns/op	   7200028 objects/sec	     132 B/op	       1 allocs/op
Benchmark_txn_delete_100-4          	10795306	       110.2 ns/op	   9072311 objects/sec	      60 B/op	       1 allocs/op
Benchmark_txn_delete_1000-4         	11536909	       106.4 ns/op	   9399148 objects/sec	      26 B/op	       1 allocs/op
Benchmark_Get-4                     	   38018	     30721 ns/op	  32551548 objects/sec	       0 B/op	       0 allocs/op
Benchmark_Iterate-4                 	  172851	      6938 ns/op	 144134974 objects/sec	      80 B/op	       3 allocs/op
Benchmark_Hashmap_Insert-4          	   15686	     76051 ns/op	  13149062 objects/sec	   86549 B/op	      64 allocs/op
Benchmark_Hashmap_Get_Uint64-4      	  164020	      7450 ns/op	 134233166 objects/sec	       0 B/op	       0 allocs/op
Benchmark_Hashmap_Get_Bytes-4       	  155763	      7682 ns/op	 130175919 objects/sec	       0 B/op	       0 allocs/op
Benchmark_Uint64Map_Random-4        	    1399	    848544 ns/op	   1178491 items/sec	 2701287 B/op	    9028 allocs/op
Benchmark_Uint64Map_Sequential-4    	    1508	    791196 ns/op	   1263910 items/sec	 2492405 B/op	    9749 allocs/op
PASS
ok  	github.com/cilium/statedb/part	28.284s
PASS
ok  	github.com/cilium/statedb/reconciler	0.004s
?   	github.com/cilium/statedb/reconciler/benchmark	[no test files]
?   	github.com/cilium/statedb/reconciler/example	[no test files]
go run ./reconciler/benchmark -quiet
1000000 objects reconciled in 2.90 seconds (batch size 1000)
Throughput 344365.87 objects per second
Allocated 6011442 objects, 424776kB bytes, 516056kB bytes still in use

[pippolo84]

💯