Move SQLDelight to data module (#8954)

And use tachiyomi instead of eu.kanade.tachiyomi for package names in the module

data/src/main/java/tachiyomi/data/AndroidDatabaseHandler.kt

@@ -0,0 +1,89 @@
+package tachiyomi.data
+
+import androidx.paging.PagingSource
+import com.squareup.sqldelight.Query
+import com.squareup.sqldelight.db.SqlDriver
+import com.squareup.sqldelight.runtime.coroutines.asFlow
+import com.squareup.sqldelight.runtime.coroutines.mapToList
+import com.squareup.sqldelight.runtime.coroutines.mapToOne
+import com.squareup.sqldelight.runtime.coroutines.mapToOneOrNull
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.withContext
+
+class AndroidDatabaseHandler(
+    val db: Database,
+    private val driver: SqlDriver,
+    val queryDispatcher: CoroutineDispatcher = Dispatchers.IO,
+    val transactionDispatcher: CoroutineDispatcher = queryDispatcher,
+) : DatabaseHandler {
+
+    val suspendingTransactionId = ThreadLocal<Int>()
+
+    override suspend fun <T> await(inTransaction: Boolean, block: suspend Database.() -> T): T {
+        return dispatch(inTransaction, block)
+    }
+
+    override suspend fun <T : Any> awaitList(
+        inTransaction: Boolean,
+        block: suspend Database.() -> Query<T>,
+    ): List<T> {
+        return dispatch(inTransaction) { block(db).executeAsList() }
+    }
+
+    override suspend fun <T : Any> awaitOne(
+        inTransaction: Boolean,
+        block: suspend Database.() -> Query<T>,
+    ): T {
+        return dispatch(inTransaction) { block(db).executeAsOne() }
+    }
+
+    override suspend fun <T : Any> awaitOneOrNull(
+        inTransaction: Boolean,
+        block: suspend Database.() -> Query<T>,
+    ): T? {
+        return dispatch(inTransaction) { block(db).executeAsOneOrNull() }
+    }
+
+    override fun <T : Any> subscribeToList(block: Database.() -> Query<T>): Flow<List<T>> {
+        return block(db).asFlow().mapToList(queryDispatcher)
+    }
+
+    override fun <T : Any> subscribeToOne(block: Database.() -> Query<T>): Flow<T> {
+        return block(db).asFlow().mapToOne(queryDispatcher)
+    }
+
+    override fun <T : Any> subscribeToOneOrNull(block: Database.() -> Query<T>): Flow<T?> {
+        return block(db).asFlow().mapToOneOrNull(queryDispatcher)
+    }
+
+    override fun <T : Any> subscribeToPagingSource(
+        countQuery: Database.() -> Query<Long>,
+        queryProvider: Database.(Long, Long) -> Query<T>,
+    ): PagingSource<Long, T> {
+        return QueryPagingSource(
+            handler = this,
+            countQuery = countQuery,
+            queryProvider = { limit, offset ->
+                queryProvider.invoke(db, limit, offset)
+            },
+        )
+    }
+
+    private suspend fun <T> dispatch(inTransaction: Boolean, block: suspend Database.() -> T): T {
+        // Create a transaction if needed and run the calling block inside it.
+        if (inTransaction) {
+            return withTransaction { block(db) }
+        }
+
+        // If we're currently in the transaction thread, there's no need to dispatch our query.
+        if (driver.currentTransaction() != null) {
+            return block(db)
+        }
+
+        // Get the current database context and run the calling block.
+        val context = getCurrentDatabaseContext()
+        return withContext(context) { block(db) }
+    }
+}

data/src/main/java/tachiyomi/data/DatabaseAdapter.kt

@@ -0,0 +1,30 @@
+package tachiyomi.data
+
+import com.squareup.sqldelight.ColumnAdapter
+import eu.kanade.tachiyomi.source.model.UpdateStrategy
+import java.util.Date
+
+val dateAdapter = object : ColumnAdapter<Date, Long> {
+    override fun decode(databaseValue: Long): Date = Date(databaseValue)
+    override fun encode(value: Date): Long = value.time
+}
+
+private const val listOfStringsSeparator = ", "
+val listOfStringsAdapter = object : ColumnAdapter<List<String>, String> {
+    override fun decode(databaseValue: String) =
+        if (databaseValue.isEmpty()) {
+            emptyList()
+        } else {
+            databaseValue.split(listOfStringsSeparator)
+        }
+    override fun encode(value: List<String>) = value.joinToString(separator = listOfStringsSeparator)
+}
+
+val updateStrategyAdapter = object : ColumnAdapter<UpdateStrategy, Long> {
+    private val enumValues by lazy { UpdateStrategy.values() }
+
+    override fun decode(databaseValue: Long): UpdateStrategy =
+        enumValues.getOrElse(databaseValue.toInt()) { UpdateStrategy.ALWAYS_UPDATE }
+
+    override fun encode(value: UpdateStrategy): Long = value.ordinal.toLong()
+}

data/src/main/java/tachiyomi/data/DatabaseHandler.kt

@@ -0,0 +1,36 @@
+package tachiyomi.data
+
+import androidx.paging.PagingSource
+import com.squareup.sqldelight.Query
+import kotlinx.coroutines.flow.Flow
+
+interface DatabaseHandler {
+
+    suspend fun <T> await(inTransaction: Boolean = false, block: suspend Database.() -> T): T
+
+    suspend fun <T : Any> awaitList(
+        inTransaction: Boolean = false,
+        block: suspend Database.() -> Query<T>,
+    ): List<T>
+
+    suspend fun <T : Any> awaitOne(
+        inTransaction: Boolean = false,
+        block: suspend Database.() -> Query<T>,
+    ): T
+
+    suspend fun <T : Any> awaitOneOrNull(
+        inTransaction: Boolean = false,
+        block: suspend Database.() -> Query<T>,
+    ): T?
+
+    fun <T : Any> subscribeToList(block: Database.() -> Query<T>): Flow<List<T>>
+
+    fun <T : Any> subscribeToOne(block: Database.() -> Query<T>): Flow<T>
+
+    fun <T : Any> subscribeToOneOrNull(block: Database.() -> Query<T>): Flow<T?>
+
+    fun <T : Any> subscribeToPagingSource(
+        countQuery: Database.() -> Query<Long>,
+        queryProvider: Database.(Long, Long) -> Query<T>,
+    ): PagingSource<Long, T>
+}

data/src/main/java/tachiyomi/data/QueryPagingSource.kt

@@ -0,0 +1,71 @@
+package tachiyomi.data
+
+import androidx.paging.PagingSource
+import androidx.paging.PagingState
+import com.squareup.sqldelight.Query
+import kotlin.properties.Delegates
+
+class QueryPagingSource<RowType : Any>(
+    val handler: DatabaseHandler,
+    val countQuery: Database.() -> Query<Long>,
+    val queryProvider: Database.(Long, Long) -> Query<RowType>,
+) : PagingSource<Long, RowType>(), Query.Listener {
+
+    override val jumpingSupported: Boolean = true
+
+    private var currentQuery: Query<RowType>? by Delegates.observable(null) { _, old, new ->
+        old?.removeListener(this)
+        new?.addListener(this)
+    }
+
+    init {
+        registerInvalidatedCallback {
+            currentQuery?.removeListener(this)
+            currentQuery = null
+        }
+    }
+
+    override suspend fun load(params: LoadParams<Long>): LoadResult<Long, RowType> {
+        try {
+            val key = params.key ?: 0L
+            val loadSize = params.loadSize
+            val count = handler.awaitOne { countQuery() }
+
+            val (offset, limit) = when (params) {
+                is LoadParams.Prepend -> key - loadSize to loadSize.toLong()
+                else -> key to loadSize.toLong()
+            }
+
+            val data = handler.awaitList {
+                queryProvider(limit, offset)
+                    .also { currentQuery = it }
+            }
+
+            val (prevKey, nextKey) = when (params) {
+                is LoadParams.Append -> { offset - loadSize to offset + loadSize }
+                else -> { offset to offset + loadSize }
+            }
+
+            return LoadResult.Page(
+                data = data,
+                prevKey = if (offset <= 0L || prevKey < 0L) null else prevKey,
+                nextKey = if (offset + loadSize >= count) null else nextKey,
+                itemsBefore = maxOf(0L, offset).toInt(),
+                itemsAfter = maxOf(0L, count - (offset + loadSize)).toInt(),
+            )
+        } catch (e: Exception) {
+            return LoadResult.Error(throwable = e)
+        }
+    }
+
+    override fun getRefreshKey(state: PagingState<Long, RowType>): Long? {
+        return state.anchorPosition?.let { anchorPosition ->
+            val anchorPage = state.closestPageToPosition(anchorPosition)
+            anchorPage?.prevKey ?: anchorPage?.nextKey
+        }
+    }
+
+    override fun queryResultsChanged() {
+        invalidate()
+    }
+}

data/src/main/java/tachiyomi/data/TransactionContext.kt

@@ -0,0 +1,161 @@
+package tachiyomi.data
+
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.asContextElement
+import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.suspendCancellableCoroutine
+import kotlinx.coroutines.withContext
+import java.util.concurrent.RejectedExecutionException
+import java.util.concurrent.atomic.AtomicInteger
+import kotlin.coroutines.ContinuationInterceptor
+import kotlin.coroutines.CoroutineContext
+import kotlin.coroutines.EmptyCoroutineContext
+import kotlin.coroutines.coroutineContext
+import kotlin.coroutines.resume
+
+/**
+ * Returns the transaction dispatcher if we are on a transaction, or the database dispatchers.
+ */
+internal suspend fun AndroidDatabaseHandler.getCurrentDatabaseContext(): CoroutineContext {
+    return coroutineContext[TransactionElement]?.transactionDispatcher ?: queryDispatcher
+}
+
+/**
+ * Calls the specified suspending [block] in a database transaction. The transaction will be
+ * marked as successful unless an exception is thrown in the suspending [block] or the coroutine
+ * is cancelled.
+ *
+ * SQLDelight will only perform at most one transaction at a time, additional transactions are queued
+ * and executed on a first come, first serve order.
+ *
+ * Performing blocking database operations is not permitted in a coroutine scope other than the
+ * one received by the suspending block. It is recommended that all [Dao] function invoked within
+ * the [block] be suspending functions.
+ *
+ * The dispatcher used to execute the given [block] will utilize threads from SQLDelight's query executor.
+ */
+internal suspend fun <T> AndroidDatabaseHandler.withTransaction(block: suspend () -> T): T {
+    // Use inherited transaction context if available, this allows nested suspending transactions.
+    val transactionContext =
+        coroutineContext[TransactionElement]?.transactionDispatcher ?: createTransactionContext()
+    return withContext(transactionContext) {
+        val transactionElement = coroutineContext[TransactionElement]!!
+        transactionElement.acquire()
+        try {
+            db.transactionWithResult {
+                runBlocking(transactionContext) {
+                    block()
+                }
+            }
+        } finally {
+            transactionElement.release()
+        }
+    }
+}
+
+/**
+ * Creates a [CoroutineContext] for performing database operations within a coroutine transaction.
+ *
+ * The context is a combination of a dispatcher, a [TransactionElement] and a thread local element.
+ *
+ * * The dispatcher will dispatch coroutines to a single thread that is taken over from the SQLDelight
+ * query executor. If the coroutine context is switched, suspending DAO functions will be able to
+ * dispatch to the transaction thread.
+ *
+ * * The [TransactionElement] serves as an indicator for inherited context, meaning, if there is a
+ * switch of context, suspending DAO methods will be able to use the indicator to dispatch the
+ * database operation to the transaction thread.
+ *
+ * * The thread local element serves as a second indicator and marks threads that are used to
+ * execute coroutines within the coroutine transaction, more specifically it allows us to identify
+ * if a blocking DAO method is invoked within the transaction coroutine. Never assign meaning to
+ * this value, for now all we care is if its present or not.
+ */
+private suspend fun AndroidDatabaseHandler.createTransactionContext(): CoroutineContext {
+    val controlJob = Job()
+    // make sure to tie the control job to this context to avoid blocking the transaction if
+    // context get cancelled before we can even start using this job. Otherwise, the acquired
+    // transaction thread will forever wait for the controlJob to be cancelled.
+    // see b/148181325
+    coroutineContext[Job]?.invokeOnCompletion {
+        controlJob.cancel()
+    }
+
+    val dispatcher = transactionDispatcher.acquireTransactionThread(controlJob)
+    val transactionElement = TransactionElement(controlJob, dispatcher)
+    val threadLocalElement =
+        suspendingTransactionId.asContextElement(System.identityHashCode(controlJob))
+    return dispatcher + transactionElement + threadLocalElement
+}
+
+/**
+ * Acquires a thread from the executor and returns a [ContinuationInterceptor] to dispatch
+ * coroutines to the acquired thread. The [controlJob] is used to control the release of the
+ * thread by cancelling the job.
+ */
+private suspend fun CoroutineDispatcher.acquireTransactionThread(
+    controlJob: Job,
+): ContinuationInterceptor {
+    return suspendCancellableCoroutine { continuation ->
+        continuation.invokeOnCancellation {
+            // We got cancelled while waiting to acquire a thread, we can't stop our attempt to
+            // acquire a thread, but we can cancel the controlling job so once it gets acquired it
+            // is quickly released.
+            controlJob.cancel()
+        }
+        try {
+            dispatch(EmptyCoroutineContext) {
+                runBlocking {
+                    // Thread acquired, resume coroutine
+                    continuation.resume(coroutineContext[ContinuationInterceptor]!!)
+                    controlJob.join()
+                }
+            }
+        } catch (ex: RejectedExecutionException) {
+            // Couldn't acquire a thread, cancel coroutine
+            continuation.cancel(
+                IllegalStateException(
+                    "Unable to acquire a thread to perform the database transaction",
+                    ex,
+                ),
+            )
+        }
+    }
+}
+
+/**
+ * A [CoroutineContext.Element] that indicates there is an on-going database transaction.
+ */
+private class TransactionElement(
+    private val transactionThreadControlJob: Job,
+    val transactionDispatcher: ContinuationInterceptor,
+) : CoroutineContext.Element {
+
+    companion object Key : CoroutineContext.Key<TransactionElement>
+
+    override val key: CoroutineContext.Key<TransactionElement>
+        get() = TransactionElement
+
+    /**
+     * Number of transactions (including nested ones) started with this element.
+     * Call [acquire] to increase the count and [release] to decrease it. If the count reaches zero
+     * when [release] is invoked then the transaction job is cancelled and the transaction thread
+     * is released.
+     */
+    private val referenceCount = AtomicInteger(0)
+
+    fun acquire() {
+        referenceCount.incrementAndGet()
+    }
+
+    fun release() {
+        val count = referenceCount.decrementAndGet()
+        if (count < 0) {
+            throw IllegalStateException("Transaction was never started or was already released")
+        } else if (count == 0) {
+            // Cancel the job that controls the transaction thread, causing it to be released.
+            transactionThreadControlJob.cancel()
+        }
+    }
+}