From 2b30685427500c9eedac4c0c4862b32af144a90c Mon Sep 17 00:00:00 2001
From: George Hazan <ghazan@miranda.im>
Date: Wed, 13 May 2020 16:09:27 +0300
Subject: kinda first working version of database event cursors

---
 plugins/Dbx_mdbx/src/dbevents.cpp | 105 +++++++++++++++++++++-----------------
 plugins/Dbx_mdbx/src/dbintf.h     |  21 +-------
 2 files changed, 59 insertions(+), 67 deletions(-)

(limited to 'plugins/Dbx_mdbx/src')

diff --git a/plugins/Dbx_mdbx/src/dbevents.cpp b/plugins/Dbx_mdbx/src/dbevents.cpp
index e435e4b975..f065989221 100644
--- a/plugins/Dbx_mdbx/src/dbevents.cpp
+++ b/plugins/Dbx_mdbx/src/dbevents.cpp
@@ -623,41 +623,66 @@ MEVENT CDbxMDBX::FindPrevEvent(MCONTACT contactID, MEVENT hDbEvent)
 /////////////////////////////////////////////////////////////////////////////////////////
 // Event cursors
 
-CMdbxEventCursor::CMdbxEventCursor(CDbxMDBX *pDb, MCONTACT hContact, DBEVENTINFO &dbei, bool bForward) :
-	EventCursor(hContact, dbei),
-	m_bForward(bForward)
+class CMdbxEventCursor : public DB::EventCursor
 {
-	mdbx_txn_begin(pDb->m_env, nullptr, MDBX_RDONLY, &m_txn_ro);
-	mdbx_cursor_open(m_txn_ro, pDb->m_dbEventsSort, &m_cursor);
-
-	m_key.hContact = hContact;
-	if (bForward) {
-		m_key.hEvent = 0;
-		m_key.ts = 0;
-	}
-	else {
-		m_key.hEvent = 0xFFFFFFFF;
-		m_key.ts = 0xFFFFFFFFFFFFFFFF;
+	friend class CDbxMDBX;
+	CDbxMDBX *m_pOwner;
+
+	bool m_bForward, m_bFirst = true;
+	DBCachedContact *m_cc;
+	DBEventSortingKey m_key;
+
+public:
+	CMdbxEventCursor(class CDbxMDBX *pDb, DBCachedContact *cc, bool bForward) :
+		EventCursor(cc->contactID),
+		m_pOwner(pDb),
+		m_bForward(bForward),
+		m_cc(cc)
+	{
+		m_key.hContact = hContact;
+		if (bForward) {
+			m_key.hEvent = 0;
+			m_key.ts = 0;
+		}
+		else {
+			m_key.hEvent = 0xFFFFFFFF;
+			m_key.ts = 0xFFFFFFFFFFFFFFFF;
+		}
 	}
-}
 
-CMdbxEventCursor::~CMdbxEventCursor()
-{
-	if (m_cursor)
-		mdbx_cursor_close(m_cursor);
-}
+	MEVENT FetchNext() override
+	{
+		MDBX_cursor_op op;
+		if (m_bFirst) {
+			op = MDBX_SET_RANGE;
+			m_bFirst = false;
+		}
+		else {
+			op = (m_bForward) ? MDBX_NEXT : MDBX_PREV;
+			if (m_key.hEvent != m_cc->t_evLast)
+				return 0;
+		}
 
-MEVENT CMdbxEventCursor::FetchNext()
-{
-	MDBX_val key = { &m_key, sizeof(m_key) }, data;
-	if (mdbx_cursor_get(*this, &key, &data, m_bForward ? MDBX_NEXT : MDBX_PREV) != MDBX_SUCCESS)
-		return 0;
+		txn_ptr_ro txn(m_pOwner->m_txn_ro);
 
-	const DBEventSortingKey *pKey = (const DBEventSortingKey *)key.iov_base;
-	return (pKey->hContact == hContact) ? pKey->hEvent : 0;
-}
+		MDBX_val key = { &m_key, sizeof(m_key) }, data;
+		if (mdbx_cursor_get(m_pOwner->m_curEventsSort, &key, &data, op) != MDBX_SUCCESS)
+			return 0;
+
+		const DBEventSortingKey *pKey = (const DBEventSortingKey *)key.iov_base;
+		if (pKey->hContact != hContact) {
+			m_cc->t_tsLast = 0;
+			return m_cc->t_evLast = 0;
+		}
+		
+		m_key = *pKey;
+		m_cc->t_evLast = pKey->hEvent;
+		m_cc->t_tsLast = pKey->ts;
+		return pKey->hEvent;
+	}
+};
 
-DB::EventCursor* CDbxMDBX::EventCursor(MCONTACT hContact, DBEVENTINFO &dbei)
+DB::EventCursor* CDbxMDBX::EventCursor(MCONTACT hContact, MEVENT)
 {
 	DBCachedContact *cc;
 	if (hContact != 0) {
@@ -667,18 +692,10 @@ DB::EventCursor* CDbxMDBX::EventCursor(MCONTACT hContact, DBEVENTINFO &dbei)
 	}
 	else cc = &m_ccDummy;
 
-	auto *pCursor = new CMdbxEventCursor(this, hContact, dbei, true);
-
-	MDBX_val key = { &pCursor->m_key, sizeof(pCursor->m_key) }, data;
-	if (mdbx_cursor_get(*pCursor, &key, &data, MDBX_SET_RANGE) != MDBX_SUCCESS) {
-		delete pCursor;
-		return nullptr;
-	}
-
-	return pCursor;
+	return new CMdbxEventCursor(this, cc, true);
 }
 
-DB::EventCursor* CDbxMDBX::EventCursorRev(MCONTACT hContact, DBEVENTINFO &dbei)
+DB::EventCursor* CDbxMDBX::EventCursorRev(MCONTACT hContact, MEVENT)
 {
 	DBCachedContact *cc;
 	if (hContact != 0) {
@@ -688,13 +705,5 @@ DB::EventCursor* CDbxMDBX::EventCursorRev(MCONTACT hContact, DBEVENTINFO &dbei)
 	}
 	else cc = &m_ccDummy;
 
-	auto *pCursor = new CMdbxEventCursor(this, hContact, dbei, false);
-
-	MDBX_val key = { &pCursor->m_key, sizeof(pCursor->m_key) }, data;
-	if (mdbx_cursor_get(*pCursor, &key, &data, MDBX_SET_RANGE) != MDBX_SUCCESS) {
-		delete pCursor;
-		return nullptr;
-	}
-
-	return pCursor;
+	return new CMdbxEventCursor(this, cc, false);
 }
diff --git a/plugins/Dbx_mdbx/src/dbintf.h b/plugins/Dbx_mdbx/src/dbintf.h
index 05687bbfd2..06602c8632 100644
--- a/plugins/Dbx_mdbx/src/dbintf.h
+++ b/plugins/Dbx_mdbx/src/dbintf.h
@@ -136,23 +136,6 @@ struct EventItem
 	MEVENT eventId;
 };
 
-class CMdbxEventCursor : public DB::EventCursor
-{
-	CMDBX_txn_ro m_txn_ro;
-	MDBX_cursor* m_cursor = nullptr;
-	bool m_bForward;
-
-public:
-	CMdbxEventCursor(class CDbxMDBX *pOdb, MCONTACT hContact, DBEVENTINFO &dbei, bool bForward);
-	~CMdbxEventCursor() override;
-
-	MEVENT FetchNext() override;
-
-	DBEventSortingKey m_key;
-
-	__forceinline operator MDBX_cursor*() const { return m_cursor; }
-};
-
 class CDbxMDBX : public MDatabaseCommon, public MZeroedObject
 {
 	friend class CMdbxEventCursor;
@@ -315,8 +298,8 @@ public:
 	STDMETHODIMP_(MEVENT)   GetEventById(LPCSTR szModule, LPCSTR szId) override;
 	STDMETHODIMP_(BOOL)     SetEventId(LPCSTR szModule, MEVENT, LPCSTR szId) override;
 
-	STDMETHODIMP_(DB::EventCursor *) EventCursor(MCONTACT hContact, DBEVENTINFO &dbei) override;
-	STDMETHODIMP_(DB::EventCursor *) EventCursorRev(MCONTACT hContact, DBEVENTINFO &dbei) override;
+	STDMETHODIMP_(DB::EventCursor *) EventCursor(MCONTACT hContact, MEVENT hDbEvent) override;
+	STDMETHODIMP_(DB::EventCursor *) EventCursorRev(MCONTACT hContact, MEVENT hDbEvent) override;
 
 public:
 	MICryptoEngine *m_crypto;
-- 
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