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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-28 09:34:30 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-28 09:34:30 +0000
commit4fc2f55f761d71aae1f145d5aa94ba929cc39676 (patch)
tree5c1e1db3b46dd4edbe11f612d93cb94b96891ce3 /ext/lmdb-safe/lmdb-safe.hh
parentInitial commit. (diff)
downloaddnsdist-4fc2f55f761d71aae1f145d5aa94ba929cc39676.tar.xz
dnsdist-4fc2f55f761d71aae1f145d5aa94ba929cc39676.zip
Adding upstream version 1.7.3.upstream/1.7.3upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'ext/lmdb-safe/lmdb-safe.hh')
-rw-r--r--ext/lmdb-safe/lmdb-safe.hh610
1 files changed, 610 insertions, 0 deletions
diff --git a/ext/lmdb-safe/lmdb-safe.hh b/ext/lmdb-safe/lmdb-safe.hh
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+++ b/ext/lmdb-safe/lmdb-safe.hh
@@ -0,0 +1,610 @@
+#pragma once
+#include <lmdb.h>
+#include <iostream>
+#include <fstream>
+#include <set>
+#include <map>
+#include <thread>
+#include <memory>
+#include <string>
+#include <string.h>
+#include <mutex>
+#include <vector>
+#include <algorithm>
+
+using std::string_view;
+
+/* open issues:
+ *
+ * - missing convenience functions (string_view, string)
+ */
+
+/*
+The error strategy. Anything that "should never happen" turns into an exception. But things like 'duplicate entry' or 'no such key' are for you to deal with.
+ */
+
+/*
+ Thread safety: we are as safe as lmdb. You can talk to MDBEnv from as many threads as you want
+*/
+
+/** MDBDbi is our only 'value type' object, as 1) a dbi is actually an integer
+ and 2) per LMDB documentation, we never close it. */
+class MDBDbi
+{
+public:
+ MDBDbi(): d_dbi(-1)
+ {
+ }
+ explicit MDBDbi(MDB_env* env, MDB_txn* txn, string_view dbname, int flags);
+
+ operator const MDB_dbi&() const
+ {
+ return d_dbi;
+ }
+
+ MDB_dbi d_dbi;
+};
+
+class MDBRWTransactionImpl;
+class MDBROTransactionImpl;
+
+using MDBROTransaction = std::unique_ptr<MDBROTransactionImpl>;
+using MDBRWTransaction = std::unique_ptr<MDBRWTransactionImpl>;
+
+class MDBEnv
+{
+public:
+ MDBEnv(const char* fname, int flags, int mode);
+
+ ~MDBEnv()
+ {
+ // Only a single thread may call this function. All transactions, databases, and cursors must already be closed before calling this function
+ mdb_env_close(d_env);
+ // but, elsewhere, docs say database handles do not need to be closed?
+ }
+
+ MDBDbi openDB(const string_view dbname, int flags);
+
+ MDBRWTransaction getRWTransaction();
+ MDBROTransaction getROTransaction();
+
+ operator MDB_env*& ()
+ {
+ return d_env;
+ }
+ MDB_env* d_env;
+
+ int getRWTX();
+ void incRWTX();
+ void decRWTX();
+ int getROTX();
+ void incROTX();
+ void decROTX();
+private:
+ std::mutex d_openmut;
+ std::mutex d_countmutex;
+ std::map<std::thread::id, int> d_RWtransactionsOut;
+ std::map<std::thread::id, int> d_ROtransactionsOut;
+};
+
+std::shared_ptr<MDBEnv> getMDBEnv(const char* fname, int flags, int mode);
+
+
+
+struct MDBOutVal
+{
+ operator MDB_val&()
+ {
+ return d_mdbval;
+ }
+
+ template <class T,
+ typename std::enable_if<std::is_arithmetic<T>::value,
+ T>::type* = nullptr> const
+ T get()
+ {
+ T ret;
+ if(d_mdbval.mv_size != sizeof(T))
+ throw std::runtime_error("MDB data has wrong length for type");
+
+ memcpy(&ret, d_mdbval.mv_data, sizeof(T));
+ return ret;
+ }
+
+ template <class T,
+ typename std::enable_if<std::is_class<T>::value,T>::type* = nullptr>
+ T get() const;
+
+ template<class T>
+ T get_struct() const
+ {
+ T ret;
+ if(d_mdbval.mv_size != sizeof(T))
+ throw std::runtime_error("MDB data has wrong length for type");
+
+ memcpy(&ret, d_mdbval.mv_data, sizeof(T));
+ return ret;
+ }
+
+ template<class T>
+ const T* get_struct_ptr() const
+ {
+ if(d_mdbval.mv_size != sizeof(T))
+ throw std::runtime_error("MDB data has wrong length for type");
+
+ return reinterpret_cast<const T*>(d_mdbval.mv_data);
+ }
+
+
+ MDB_val d_mdbval;
+};
+
+template<> inline std::string MDBOutVal::get<std::string>() const
+{
+ return std::string((char*)d_mdbval.mv_data, d_mdbval.mv_size);
+}
+
+template<> inline string_view MDBOutVal::get<string_view>() const
+{
+ return string_view((char*)d_mdbval.mv_data, d_mdbval.mv_size);
+}
+
+class MDBInVal
+{
+public:
+ MDBInVal(const MDBOutVal& rhs): d_mdbval(rhs.d_mdbval)
+ {
+ }
+
+ template <class T,
+ typename std::enable_if<std::is_arithmetic<T>::value,
+ T>::type* = nullptr>
+ MDBInVal(T i)
+ {
+ memcpy(&d_memory[0], &i, sizeof(i));
+ d_mdbval.mv_size = sizeof(T);
+ d_mdbval.mv_data = d_memory;;
+ }
+
+ MDBInVal(const char* s)
+ {
+ d_mdbval.mv_size = strlen(s);
+ d_mdbval.mv_data = (void*)s;
+ }
+
+ MDBInVal(const string_view& v)
+ {
+ d_mdbval.mv_size = v.size();
+ d_mdbval.mv_data = (void*)&v[0];
+ }
+
+ MDBInVal(const std::string& v)
+ {
+ d_mdbval.mv_size = v.size();
+ d_mdbval.mv_data = (void*)&v[0];
+ }
+
+
+ template<typename T>
+ static MDBInVal fromStruct(const T& t)
+ {
+ MDBInVal ret;
+ ret.d_mdbval.mv_size = sizeof(T);
+ ret.d_mdbval.mv_data = (void*)&t;
+ return ret;
+ }
+
+ operator MDB_val&()
+ {
+ return d_mdbval;
+ }
+ MDB_val d_mdbval;
+private:
+ MDBInVal(){}
+ char d_memory[sizeof(double)];
+
+};
+
+
+
+
+class MDBROCursor;
+
+class MDBROTransactionImpl
+{
+protected:
+ MDBROTransactionImpl(MDBEnv *parent, MDB_txn *txn);
+
+private:
+ static MDB_txn *openROTransaction(MDBEnv *env, MDB_txn *parent, int flags=0);
+
+ MDBEnv* d_parent;
+ std::vector<MDBROCursor*> d_cursors;
+
+protected:
+ MDB_txn* d_txn;
+
+ void closeROCursors();
+
+public:
+ explicit MDBROTransactionImpl(MDBEnv* parent, int flags=0);
+
+ MDBROTransactionImpl(const MDBROTransactionImpl& src) = delete;
+ MDBROTransactionImpl &operator=(const MDBROTransactionImpl& src) = delete;
+
+ // The move constructor/operator cannot be made safe due to Object Slicing with MDBRWTransaction.
+ MDBROTransactionImpl(MDBROTransactionImpl&& rhs) = delete;
+ MDBROTransactionImpl &operator=(MDBROTransactionImpl &&rhs) = delete;
+
+ virtual ~MDBROTransactionImpl();
+
+ virtual void abort();
+ virtual void commit();
+
+ int get(MDB_dbi dbi, const MDBInVal& key, MDBOutVal& val)
+ {
+ if(!d_txn)
+ throw std::runtime_error("Attempt to use a closed RO transaction for get");
+
+ int rc = mdb_get(d_txn, dbi, const_cast<MDB_val*>(&key.d_mdbval),
+ const_cast<MDB_val*>(&val.d_mdbval));
+ if(rc && rc != MDB_NOTFOUND)
+ throw std::runtime_error("getting data: " + std::string(mdb_strerror(rc)));
+
+ return rc;
+ }
+
+ int get(MDB_dbi dbi, const MDBInVal& key, string_view& val)
+ {
+ MDBOutVal out;
+ int rc = get(dbi, key, out);
+ if(!rc)
+ val = out.get<string_view>();
+ return rc;
+ }
+
+
+ // this is something you can do, readonly
+ MDBDbi openDB(string_view dbname, int flags)
+ {
+ return MDBDbi( d_parent->d_env, d_txn, dbname, flags);
+ }
+
+ MDBROCursor getCursor(const MDBDbi&);
+ MDBROCursor getROCursor(const MDBDbi&);
+
+ operator MDB_txn*()
+ {
+ return d_txn;
+ }
+
+ inline operator bool() const {
+ return d_txn;
+ }
+
+ inline MDBEnv &environment()
+ {
+ return *d_parent;
+ }
+};
+
+/*
+ A cursor in a read-only transaction must be closed explicitly, before or after its transaction ends. It can be reused with mdb_cursor_renew() before finally closing it.
+
+ "If the parent transaction commits, the cursor must not be used again."
+*/
+
+template<class Transaction, class T>
+class MDBGenCursor
+{
+private:
+ std::vector<T*> *d_registry;
+ MDB_cursor* d_cursor{nullptr};
+
+public:
+ MDBGenCursor():
+ d_registry(nullptr),
+ d_cursor(nullptr)
+ {
+
+ }
+
+ MDBGenCursor(std::vector<T*> &registry, MDB_cursor *cursor):
+ d_registry(&registry),
+ d_cursor(cursor)
+ {
+ registry.emplace_back(static_cast<T*>(this));
+ }
+
+private:
+ void move_from(MDBGenCursor *src)
+ {
+ if (!d_registry) {
+ return;
+ }
+
+ auto iter = std::find(d_registry->begin(),
+ d_registry->end(),
+ src);
+ if (iter != d_registry->end()) {
+ *iter = static_cast<T*>(this);
+ } else {
+ d_registry->emplace_back(static_cast<T*>(this));
+ }
+ }
+
+public:
+ MDBGenCursor(const MDBGenCursor &src) = delete;
+
+ MDBGenCursor(MDBGenCursor &&src) noexcept:
+ d_registry(src.d_registry),
+ d_cursor(src.d_cursor)
+ {
+ move_from(&src);
+ src.d_registry = nullptr;
+ src.d_cursor = nullptr;
+ }
+
+ MDBGenCursor &operator=(const MDBGenCursor &src) = delete;
+
+ MDBGenCursor &operator=(MDBGenCursor &&src) noexcept
+ {
+ d_registry = src.d_registry;
+ d_cursor = src.d_cursor;
+ move_from(&src);
+ src.d_registry = nullptr;
+ src.d_cursor = nullptr;
+ return *this;
+ }
+
+ ~MDBGenCursor()
+ {
+ close();
+ }
+
+public:
+ int get(MDBOutVal& key, MDBOutVal& data, MDB_cursor_op op)
+ {
+ int rc = mdb_cursor_get(d_cursor, &key.d_mdbval, &data.d_mdbval, op);
+ if(rc && rc != MDB_NOTFOUND)
+ throw std::runtime_error("Unable to get from cursor: " + std::string(mdb_strerror(rc)));
+ return rc;
+ }
+
+ int find(const MDBInVal& in, MDBOutVal& key, MDBOutVal& data)
+ {
+ key.d_mdbval = in.d_mdbval;
+ int rc=mdb_cursor_get(d_cursor, const_cast<MDB_val*>(&key.d_mdbval), &data.d_mdbval, MDB_SET);
+ if(rc && rc != MDB_NOTFOUND)
+ throw std::runtime_error("Unable to find from cursor: " + std::string(mdb_strerror(rc)));
+ return rc;
+ }
+
+ int lower_bound(const MDBInVal& in, MDBOutVal& key, MDBOutVal& data)
+ {
+ key.d_mdbval = in.d_mdbval;
+
+ int rc = mdb_cursor_get(d_cursor, const_cast<MDB_val*>(&key.d_mdbval), &data.d_mdbval, MDB_SET_RANGE);
+ if(rc && rc != MDB_NOTFOUND)
+ throw std::runtime_error("Unable to lower_bound from cursor: " + std::string(mdb_strerror(rc)));
+ return rc;
+ }
+
+
+ int nextprev(MDBOutVal& key, MDBOutVal& data, MDB_cursor_op op)
+ {
+ int rc = mdb_cursor_get(d_cursor, const_cast<MDB_val*>(&key.d_mdbval), &data.d_mdbval, op);
+ if(rc && rc != MDB_NOTFOUND)
+ throw std::runtime_error("Unable to prevnext from cursor: " + std::string(mdb_strerror(rc)));
+ return rc;
+ }
+
+ int next(MDBOutVal& key, MDBOutVal& data)
+ {
+ return nextprev(key, data, MDB_NEXT);
+ }
+
+ int prev(MDBOutVal& key, MDBOutVal& data)
+ {
+ return nextprev(key, data, MDB_PREV);
+ }
+
+ int currentlast(MDBOutVal& key, MDBOutVal& data, MDB_cursor_op op)
+ {
+ int rc = mdb_cursor_get(d_cursor, const_cast<MDB_val*>(&key.d_mdbval), &data.d_mdbval, op);
+ if(rc && rc != MDB_NOTFOUND)
+ throw std::runtime_error("Unable to next from cursor: " + std::string(mdb_strerror(rc)));
+ return rc;
+ }
+
+ int current(MDBOutVal& key, MDBOutVal& data)
+ {
+ return currentlast(key, data, MDB_GET_CURRENT);
+ }
+ int last(MDBOutVal& key, MDBOutVal& data)
+ {
+ return currentlast(key, data, MDB_LAST);
+ }
+ int first(MDBOutVal& key, MDBOutVal& data)
+ {
+ return currentlast(key, data, MDB_FIRST);
+ }
+
+ operator MDB_cursor*()
+ {
+ return d_cursor;
+ }
+
+ operator bool() const
+ {
+ return d_cursor;
+ }
+
+ void close()
+ {
+ if (d_registry) {
+ auto iter = std::find(d_registry->begin(),
+ d_registry->end(),
+ static_cast<T*>(this));
+ if (iter != d_registry->end()) {
+ d_registry->erase(iter);
+ }
+ d_registry = nullptr;
+ }
+ if (d_cursor) {
+ mdb_cursor_close(d_cursor);
+ d_cursor = nullptr;
+ }
+ }
+};
+
+class MDBROCursor : public MDBGenCursor<MDBROTransactionImpl, MDBROCursor>
+{
+public:
+ MDBROCursor() = default;
+ using MDBGenCursor<MDBROTransactionImpl, MDBROCursor>::MDBGenCursor;
+ MDBROCursor(const MDBROCursor &src) = delete;
+ MDBROCursor(MDBROCursor &&src) = default;
+ MDBROCursor &operator=(const MDBROCursor &src) = delete;
+ MDBROCursor &operator=(MDBROCursor &&src) = default;
+ ~MDBROCursor() = default;
+
+};
+
+class MDBRWCursor;
+
+class MDBRWTransactionImpl: public MDBROTransactionImpl
+{
+protected:
+ MDBRWTransactionImpl(MDBEnv* parent, MDB_txn* txn);
+
+private:
+ static MDB_txn *openRWTransaction(MDBEnv* env, MDB_txn *parent, int flags);
+
+private:
+ std::vector<MDBRWCursor*> d_rw_cursors;
+
+ void closeRWCursors();
+ inline void closeRORWCursors() {
+ closeROCursors();
+ closeRWCursors();
+ }
+
+public:
+ explicit MDBRWTransactionImpl(MDBEnv* parent, int flags=0);
+
+ MDBRWTransactionImpl(const MDBRWTransactionImpl& rhs) = delete;
+ MDBRWTransactionImpl(MDBRWTransactionImpl&& rhs) = delete;
+ MDBRWTransactionImpl &operator=(const MDBRWTransactionImpl& rhs) = delete;
+ MDBRWTransactionImpl &operator=(MDBRWTransactionImpl&& rhs) = delete;
+
+ ~MDBRWTransactionImpl() override;
+
+ void commit() override;
+ void abort() override;
+
+ void clear(MDB_dbi dbi);
+
+ void put(MDB_dbi dbi, const MDBInVal& key, const MDBInVal& val, int flags=0)
+ {
+ if(!d_txn)
+ throw std::runtime_error("Attempt to use a closed RW transaction for put");
+ int rc;
+ if((rc=mdb_put(d_txn, dbi,
+ const_cast<MDB_val*>(&key.d_mdbval),
+ const_cast<MDB_val*>(&val.d_mdbval), flags)))
+ throw std::runtime_error("putting data: " + std::string(mdb_strerror(rc)));
+ }
+
+
+ int del(MDBDbi& dbi, const MDBInVal& key, const MDBInVal& val)
+ {
+ int rc;
+ rc=mdb_del(d_txn, dbi, (MDB_val*)&key.d_mdbval, (MDB_val*)&val.d_mdbval);
+ if(rc && rc != MDB_NOTFOUND)
+ throw std::runtime_error("deleting data: " + std::string(mdb_strerror(rc)));
+ return rc;
+ }
+
+ int del(MDBDbi& dbi, const MDBInVal& key)
+ {
+ int rc;
+ rc=mdb_del(d_txn, dbi, (MDB_val*)&key.d_mdbval, 0);
+ if(rc && rc != MDB_NOTFOUND)
+ throw std::runtime_error("deleting data: " + std::string(mdb_strerror(rc)));
+ return rc;
+ }
+
+
+ int get(MDBDbi& dbi, const MDBInVal& key, MDBOutVal& val)
+ {
+ if(!d_txn)
+ throw std::runtime_error("Attempt to use a closed RW transaction for get");
+
+ int rc = mdb_get(d_txn, dbi, const_cast<MDB_val*>(&key.d_mdbval),
+ const_cast<MDB_val*>(&val.d_mdbval));
+ if(rc && rc != MDB_NOTFOUND)
+ throw std::runtime_error("getting data: " + std::string(mdb_strerror(rc)));
+ return rc;
+ }
+
+ int get(MDBDbi& dbi, const MDBInVal& key, string_view& val)
+ {
+ MDBOutVal out;
+ int rc = get(dbi, key, out);
+ if(!rc)
+ val = out.get<string_view>();
+ return rc;
+ }
+
+ MDBDbi openDB(string_view dbname, int flags)
+ {
+ return MDBDbi(environment().d_env, d_txn, dbname, flags);
+ }
+
+ MDBRWCursor getRWCursor(const MDBDbi&);
+ MDBRWCursor getCursor(const MDBDbi&);
+
+ MDBRWTransaction getRWTransaction();
+ MDBROTransaction getROTransaction();
+};
+
+/* "A cursor in a write-transaction can be closed before its transaction ends, and will otherwise be closed when its transaction ends"
+ This is a problem for us since it may means we are closing the cursor twice, which is bad
+*/
+class MDBRWCursor : public MDBGenCursor<MDBRWTransactionImpl, MDBRWCursor>
+{
+public:
+ MDBRWCursor() = default;
+ using MDBGenCursor<MDBRWTransactionImpl, MDBRWCursor>::MDBGenCursor;
+ MDBRWCursor(const MDBRWCursor &src) = delete;
+ MDBRWCursor(MDBRWCursor &&src) = default;
+ MDBRWCursor &operator=(const MDBRWCursor &src) = delete;
+ MDBRWCursor &operator=(MDBRWCursor &&src) = default;
+ ~MDBRWCursor() = default;
+
+ void put(const MDBOutVal& key, const MDBInVal& data)
+ {
+ int rc = mdb_cursor_put(*this,
+ const_cast<MDB_val*>(&key.d_mdbval),
+ const_cast<MDB_val*>(&data.d_mdbval), MDB_CURRENT);
+ if(rc)
+ throw std::runtime_error("mdb_cursor_put: " + std::string(mdb_strerror(rc)));
+ }
+
+
+ int put(const MDBOutVal& key, const MDBOutVal& data, int flags=0)
+ {
+ // XXX check errors
+ return mdb_cursor_put(*this,
+ const_cast<MDB_val*>(&key.d_mdbval),
+ const_cast<MDB_val*>(&data.d_mdbval), flags);
+ }
+
+ int del(int flags=0)
+ {
+ return mdb_cursor_del(*this, flags);
+ }
+
+};
+