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#include "stdafx.h"
#include "SequentialConnection.h"
namespace sql {
/**
* Connection.
*/
SequentialConnection::SequentialConnection()
: toFinalize(null), currentFetching(null) {}
void SequentialConnection::finalizeAll() {
while (toFinalize) {
finalizeStmt(toFinalize);
toFinalize = toFinalize->toFinalize;
}
}
void SequentialConnection::onFinalize(SequentialStatement *stmt) {
if (currentFetching == stmt || currentFetching == null) {
// Finalize immediately, nothing is going on.
finalizeStmt(stmt);
currentFetching = null;
} else {
// Delay finalization until no fetch is going on.
stmt->toFinalize = toFinalize;
toFinalize = stmt;
}
}
void SequentialConnection::startFetch(SequentialStatement *stmt) {
if (currentFetching != stmt)
clearFetch();
currentFetching = stmt;
}
void SequentialConnection::doneFetch(SequentialStatement *stmt) {
if (currentFetching == stmt)
currentFetching = null;
finalizeAll();
}
void SequentialConnection::clearFetch() {
if (currentFetching) {
currentFetching->fetchAll();
// Should be cleared by 'fetchAll'.
assert(currentFetching == null);
currentFetching = null;
}
}
void SequentialConnection::clearFetch(SequentialStatement *stmt) {
if (currentFetching == stmt)
return;
clearFetch();
}
Bool SequentialConnection::isFetching(SequentialStatement *stmt) {
return currentFetching == stmt;
}
/**
* Statement.
*/
SequentialStatement::SequentialStatement(SequentialConnection *owner)
: Statement(owner), owner(owner), atEnd(true) {}
SequentialStatement::~SequentialStatement() {
finalize();
}
void SequentialStatement::finalize() {
// Invalidate any existing result instances.
invalidateResult();
if (owner) {
owner->onFinalize(this);
deregister(owner);
}
// To avoid multiple finalization, for example when the parent class is closed or finalized before us.
owner = null;
}
Statement::Result SequentialStatement::execute() {
invalidateResult();
disposeResult();
owner->startFetch(this);
try {
if (executeSeq()) {
atEnd = false;
} else {
// No result, reset everything.
disposeResult();
}
return Result(this);
} catch (...) {
// Error during execute, make sure to indicate that we don't have any result.
disposeResult();
throw;
}
}
Maybe<Row> SequentialStatement::nextRow() {
Maybe<Row> out; // null by default
if (buffer) {
if (buffer->any()) {
out = Maybe<Row>(buffer->last());
buffer->pop();
} else {
buffer = null;
atEnd = true;
}
} else if (!atEnd) {
out = nextRowSeq();
if (out.empty())
fetchDone();
}
return out;
}
void SequentialStatement::disposeResult() {
// This may if the statement is explicitly finalized, but result instances linger.
if (!owner)
return;
// Note: 'dispose' may be called just about anytime, so we need to make sure to only call
// the Seq version when it is actually our turn. Otherwise we fail to uphold the Seq
// guarantees.
if (owner->isFetching(this)) {
disposeResultSeq();
owner->doneFetch(this);
}
}
void SequentialStatement::fetchDone() {
// Call dispose to help the client to clean up. We will inhibit future calls as soon as we
// call 'owner->doneFetch'.
disposeResultSeq();
atEnd = true;
owner->doneFetch(this);
}
void SequentialStatement::fetchAll() {
buffer = new (this) Array<Row>();
while (!atEnd) {
Maybe<Row> r = nextRowSeq();
if (r.any())
buffer->push(r.value());
else
fetchDone();
}
buffer->reverse();
}
}
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