add a lot of comments for future ahu
This commit is contained in:
bert hubert
parent
bb981d6d31
commit
654e782b5f
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@ -1,4 +1,6 @@
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#include "lmdb-typed.hh"
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#include <arpa/inet.h>
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#include <string>
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unsigned int getMaxID(MDBRWTransaction& txn, MDBDbi& dbi)
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@ -44,7 +46,8 @@ struct compound
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std::string operator()(const DNSResourceRecord& rr)
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{
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std::string ret;
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ret.assign((char*)&rr.domain_id, 4);
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uint32_t id = htonl(rr.domain_id);
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ret.assign((char*)&id, 4);
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ret.append(rr.ordername);
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return ret;
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}
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@ -69,7 +72,7 @@ int main()
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}
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cout<<"Iterating over name 'powerdns.com': "<<endl;
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auto range = rotxn.equal_range<0>("powerdns.com");
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for(auto& iter = range.first; iter != range.second; ++iter)
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for(auto iter = std::move(range.first); iter != range.second; ++iter)
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{
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cout << iter->qname << " " << iter->qtype << " " <<iter->content <<endl;
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}
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@ -168,13 +171,13 @@ int main()
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}
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compound c;
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rr3.ordername = "www";
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rr3.ordername = "vvv";
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rr3.domain_id = 10;
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auto iter = txn.find<2>(c(rr3));
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cout <<"Found using compound index: "<<iter->qname<< " # " <<iter->ordername<<endl;
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auto iter = txn.lower_bound<2>(c(rr3));
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cout <<"Found for '"<<rr3.ordername<<"' using compound index: "<<iter->qname<< " # '" <<iter->ordername<< "'"<<endl;
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for(int n =0 ; n < 4; ++n) {
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--iter;
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cout <<"Found PREV using compound index: "<<iter->qname<< " # " <<iter->ordername<<endl;
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cout <<"Found PREV using compound index: "<<iter->qname<< " # '" <<iter->ordername<<"'"<<endl;
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}
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cout<<"Going to iterate over the name powerdns.com!"<<endl;
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150
lmdb-typed.hh
150
lmdb-typed.hh
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@ -20,22 +20,25 @@ using std::endl;
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Everything should go into a namespace
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What is an error? What is an exception?
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could id=0 be magic? ('no such id')
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Composite keys (powerdns needs them)
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functional keys
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Insert? Put? Naming matters
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Is boost the best serializer?
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rename find to equal_range
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Perhaps use the separate index concept from multi_index
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A dump function would be nice (typed)
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*/
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/** Return the highest ID used in a database. Returns 0 for an empty DB.
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This makes us start everything at ID=1, which might make it possible to
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treat id 0 as special
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*/
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unsigned int getMaxID(MDBRWTransaction& txn, MDBDbi& dbi);
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/** This is our serialization interface.
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We could/should templatize this so you could pick something else
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*/
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template<typename T>
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std::string serToString(const T& t)
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{
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std::string serial_str;
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boost::iostreams::back_insert_device<std::string> inserter(serial_str);
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boost::iostreams::stream<boost::iostreams::back_insert_device<std::string> > s(inserter);
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@ -54,47 +57,15 @@ void serFromString(const std::string& str, T& ret)
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oi >> ret;
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}
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/** This is a struct that implements index operations, but
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only the operations that are broadcast to all indexes.
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Specifically, to deal with databases with less than the maximum
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number of interfaces, this only includes calls that should be
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ignored for empty indexes.
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/* This is for storing a struct that has to be found using several
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of its fields.
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We want a typed lmdb database that we can only:
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* insert such structs
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* remove them
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* mutate them
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All while maintaining indexes on insert, removal and mutation.
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struct DNSResourceRecord
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{
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string qname; // index
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string qtype;
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uint32_t domain_id; // index
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string content;
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string ordername; // index
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bool auth;
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}
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TypedDBI<DNSResourceRecord,
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DNSResourceRecord::qname,
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DNSResourceRecord::domain_id,
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DNSResourceRecord::ordername> tdbi;
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DNSResourceRecord rr;
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uint32_t id = tdbi.insert(rr); // inserts, creates three index items
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tdbi.modify(id, [](auto& rr) { rr.auth=false; });
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DNSResourceRecord retrr;
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uint32_t id = tdbi.get<1>(qname, retrr);
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// this checks for changes and updates indexes if need be
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tdbi.modify(id, [](auto& rr) { rr.ordername="blah"; });
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*/
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// this only needs methods that must happen for all indexes at once
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// so specifically, not size<t> or get<t>, people ask for those themselves, and
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// should no do that on indexes that don't exist
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this only needs methods that must happen for all indexes at once
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so specifically, not size<t> or get<t>, people ask for those themselves, and
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should no do that on indexes that don't exist */
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template<class Class,typename Type, typename Parent>
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struct LMDBIndexOps
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@ -118,6 +89,8 @@ struct LMDBIndexOps
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Parent* d_parent;
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};
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/** This is an index on a field in a struct, it derives from the LMDBIndexOps */
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template<class Class,typename Type,Type Class::*PtrToMember>
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struct index_on : LMDBIndexOps<Class, Type, index_on<Class, Type, PtrToMember>>
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{
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@ -131,6 +104,7 @@ struct index_on : LMDBIndexOps<Class, Type, index_on<Class, Type, PtrToMember>>
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typedef Type type;
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};
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/** This is a calculated index */
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template<class Class, typename Type, class Func>
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struct index_on_function : LMDBIndexOps<Class, Type, index_on_function<Class, Type, Func> >
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{
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@ -145,6 +119,7 @@ struct index_on_function : LMDBIndexOps<Class, Type, index_on_function<Class, Ty
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typedef Type type;
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};
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/** nop index, so we can fill our N indexes, even if you don't use them all */
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struct nullindex_t
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{
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template<typename Class>
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@ -161,6 +136,7 @@ struct nullindex_t
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typedef uint32_t type; // dummy
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};
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/** The main class. Templatized only on the indexes and typename right now */
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template<typename T, class I1=nullindex_t, class I2=nullindex_t, class I3 = nullindex_t, class I4 = nullindex_t>
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class TypedDBI
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{
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@ -169,7 +145,10 @@ public:
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: d_env(env), d_name(name)
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{
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d_main = d_env->openDB(name, MDB_CREATE | MDB_INTEGERKEY);
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// now you might be tempted to go all MPL on this so we can get rid of the
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// ugly macro. I'm not very receptive to that idea since it will make things
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// EVEN uglier.
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#define openMacro(N) std::get<N>(d_tuple).openDB(d_env, std::string(name)+"_"#N, MDB_CREATE | MDB_DUPFIXED | MDB_DUPSORT);
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openMacro(0);
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openMacro(1);
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@ -179,15 +158,19 @@ public:
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}
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// we get a lot of our smarts from this tuple, it enables get<0> etc
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typedef std::tuple<I1, I2, I3, I4> tuple_t;
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tuple_t d_tuple;
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// We support readonly and rw transactions. Here we put the Readonly operations
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// which get sourced by both kinds of transactions
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template<class Parent>
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struct ReadonlyOperations
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{
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ReadonlyOperations(Parent& parent) : d_parent(parent)
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{}
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//! Number of entries in main database
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uint32_t size()
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{
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MDB_stat stat;
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@ -195,6 +178,7 @@ public:
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return stat.ms_entries;
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}
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//! Number of entries in the various indexes - should be the same
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template<int N>
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uint32_t size()
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{
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@ -202,7 +186,8 @@ public:
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mdb_stat(d_parent.d_txn, std::get<N>(d_parent.d_parent->d_tuple).d_idx, &stat);
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return stat.ms_entries;
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}
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//! Get item with id, from main table directly
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bool get(uint32_t id, T& t)
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{
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MDBOutVal data;
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@ -213,6 +198,7 @@ public:
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return true;
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}
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//! Get item through index N, then via the main database
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template<int N>
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uint32_t get(const typename std::tuple_element<N, tuple_t>::type::type& key, T& out)
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{
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@ -222,7 +208,7 @@ public:
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return 0;
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}
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//! Cardinality of index N
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template<int N>
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uint32_t cardinality()
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{
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@ -237,21 +223,22 @@ public:
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return count;
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}
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//! End iderator type
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struct eiter_t
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{};
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// can be on main, or on an index
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// when on main, return data directly
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// when on index, indirect
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// we can be limited to one key, or iterate over entire table
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//
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// we can be limited to one key, or iterate over entire database
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// iter requires you to put the cursor in the right place first!
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struct iter_t
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{
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explicit iter_t(Parent* parent, typename Parent::cursor_t&& cursor, bool on_index, bool one_key, bool end=false) :
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d_parent(parent),
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d_cursor(std::move(cursor)),
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d_on_index(on_index),
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d_one_key(one_key),
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d_on_index(on_index), // is this an iterator on main database or on index?
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d_one_key(one_key), // should we stop at end of key? (equal range)
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d_end(end)
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{
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if(d_end)
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@ -291,7 +278,8 @@ public:
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{
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return &d_t;
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}
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// implements generic ++ or --
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iter_t& genoperator(MDB_cursor_op dupop, MDB_cursor_op op)
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{
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MDBOutVal data;
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@ -320,7 +308,8 @@ public:
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{
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return genoperator(MDB_PREV_DUP, MDB_PREV);
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}
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// get ID this iterator points to
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uint32_t getID()
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{
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if(d_on_index)
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@ -328,9 +317,12 @@ public:
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else
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return d_key.get<uint32_t>();
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}
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// transaction we are part of
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Parent* d_parent;
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typename Parent::cursor_t d_cursor;
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// gcc complains if I don't zero-init these, which is worrying XXX
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MDBOutVal d_key{0,0}, d_data{0,0}, d_id{0,0};
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bool d_on_index;
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bool d_one_key;
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@ -367,9 +359,14 @@ public:
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return iter_t{&d_parent, std::move(cursor), false, false};
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};
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eiter_t end()
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{
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return eiter_t();
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}
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// basis for find, lower_bound
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template<int N>
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iter_t find(const typename std::tuple_element<N, tuple_t>::type::type& key)
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iter_t genfind(const typename std::tuple_element<N, tuple_t>::type::type& key, MDB_cursor_op op)
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{
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typename Parent::cursor_t cursor = d_parent.d_txn.getCursor(std::get<N>(d_parent.d_parent->d_tuple).d_idx);
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@ -377,7 +374,7 @@ public:
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MDBOutVal out, id;
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out.d_mdbval = in.d_mdbval;
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if(cursor.get(out, id, MDB_SET)) {
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if(cursor.get(out, id, op)) {
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// on_index, one_key, end
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return iter_t{&d_parent, std::move(cursor), true, false, true};
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}
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@ -385,6 +382,20 @@ public:
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return iter_t{&d_parent, std::move(cursor), true, false};
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};
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template<int N>
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iter_t find(const typename std::tuple_element<N, tuple_t>::type::type& key)
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{
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return genfind<N>(key, MDB_SET);
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}
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template<int N>
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iter_t lower_bound(const typename std::tuple_element<N, tuple_t>::type::type& key)
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{
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return genfind<N>(key, MDB_SET_RANGE);
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}
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//! equal range - could possibly be expressed through genfind
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template<int N>
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std::pair<iter_t,eiter_t> equal_range(const typename std::tuple_element<N, tuple_t>::type::type& key)
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{
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@ -402,12 +413,6 @@ public:
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return {iter_t{&d_parent, std::move(cursor), true, true}, eiter_t()};
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};
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eiter_t end()
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{
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return eiter_t();
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}
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Parent& d_parent;
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};
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@ -446,7 +451,7 @@ public:
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rhs.d_parent = 0;
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}
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// insert something, with possibly a specific id
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uint32_t insert(const T& t, uint32_t id=0)
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{
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if(!id)
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@ -463,6 +468,7 @@ public:
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return id;
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}
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// modify an item 'in place', plus update indexes
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void modify(uint32_t id, std::function<void(T&)> func)
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{
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T t;
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@ -474,7 +480,7 @@ public:
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insert(t, id);
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}
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//! delete an item, and from indexes
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void del(uint32_t id)
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{
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T t;
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@ -485,6 +491,7 @@ public:
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clearIndex(id, t);
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}
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//! clear database & indexes (by hand!)
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void clear()
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{
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auto cursor = d_txn.getCursor(d_parent->d_main);
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@ -498,22 +505,23 @@ public:
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cursor.del();
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}
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}
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//! commit this transaction
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void commit()
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{
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d_txn.commit();
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}
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//! abort this transaction
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void abort()
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{
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d_txn.abort();
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}
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typedef MDBRWCursor cursor_t;
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private:
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// clear this ID from all indexes
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void clearIndex(uint32_t id, const T& t)
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{
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#define clearMacro(N) std::get<N>(d_parent->d_tuple).del(d_txn, t, id);
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@ -528,12 +536,14 @@ public:
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TypedDBI* d_parent;
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MDBRWTransaction d_txn;
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};
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//! Get an RW transaction
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RWTransaction getRWTransaction()
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{
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return RWTransaction(this);
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}
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//! Get an RO transaction
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ROTransaction getROTransaction()
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{
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return ROTransaction(this);
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