briar-headless: Inject a singleton ObjectMapper for JSON parsing

briar-headless/src/main/java/org/briarproject/briar/headless/HeadlessModule.kt

 package org.briarproject.briar.headless
 
+import com.fasterxml.jackson.databind.ObjectMapper
 import dagger.Module
 import dagger.Provides
 import org.briarproject.bramble.api.crypto.CryptoComponent
@@ -113,4 +114,8 @@ internal class HeadlessModule(private val appDir: File) {
         }
     }
 
+    @Provides
+    @Singleton
+    internal fun provideObjectMapper() = ObjectMapper()
+
 }

briar-headless/src/main/java/org/briarproject/briar/headless/Router.kt

@@ -115,10 +115,9 @@ constructor(
 /**
  * Returns a String from the JSON field or throws [BadRequestResponse] if null or empty.
  */
-fun Context.getFromJson(field: String) : String {
+fun Context.getFromJson(objectMapper: ObjectMapper, field: String) : String {
     try {
-        // TODO use a static object mapper to avoid re-initializations
-        val jsonNode = ObjectMapper().readTree(body())
+        val jsonNode = objectMapper.readTree(body())
         if (!jsonNode.hasNonNull(field)) throw BadRequestResponse("'$field' missing in JSON")
         val result = jsonNode.get(field).asText()
         if (result == null || result.isEmpty()) throw BadRequestResponse("'$field' empty in JSON")

briar-headless/src/main/java/org/briarproject/briar/headless/blogs/BlogControllerImpl.kt

 package org.briarproject.briar.headless.blogs
 
+import com.fasterxml.jackson.databind.ObjectMapper
 import io.javalin.BadRequestResponse
 import io.javalin.Context
 import org.briarproject.bramble.api.identity.IdentityManager
@@ -21,6 +22,7 @@ constructor(
     private val blogManager: BlogManager,
     private val blogPostFactory: BlogPostFactory,
     private val identityManager: IdentityManager,
+    private val objectMapper: ObjectMapper,
     private val clock: Clock
 ) : BlogController {
 
@@ -35,7 +37,7 @@ constructor(
     }
 
     override fun createPost(ctx: Context): Context {
-        val text = ctx.getFromJson("text")
+        val text = ctx.getFromJson(objectMapper, "text")
         if (utf8IsTooLong(text, MAX_BLOG_POST_TEXT_LENGTH))
             throw BadRequestResponse("Blog post text is too long")
 

briar-headless/src/main/java/org/briarproject/briar/headless/forums/ForumControllerImpl.kt

 package org.briarproject.briar.headless.forums
 
+import com.fasterxml.jackson.databind.ObjectMapper
 import io.javalin.BadRequestResponse
 import io.javalin.Context
 import org.briarproject.bramble.util.StringUtils.utf8IsTooLong
@@ -14,14 +15,15 @@ import javax.inject.Singleton
 @Singleton
 internal class ForumControllerImpl
 @Inject
-constructor(private val forumManager: ForumManager) : ForumController {
+constructor(private val forumManager: ForumManager, private val objectMapper: ObjectMapper) :
+    ForumController {
 
     override fun list(ctx: Context): Context {
         return ctx.json(forumManager.forums.output())
     }
 
     override fun create(ctx: Context): Context {
-        val name = ctx.getFromJson("name")
+        val name = ctx.getFromJson(objectMapper, "name")
         if (utf8IsTooLong(name, MAX_FORUM_NAME_LENGTH))
             throw BadRequestResponse("Forum name is too long")
         return ctx.json(forumManager.addForum(name).output())

briar-headless/src/main/java/org/briarproject/briar/headless/messaging/MessagingControllerImpl.kt

 package org.briarproject.briar.headless.messaging
 
+import com.fasterxml.jackson.databind.ObjectMapper
 import io.javalin.BadRequestResponse
 import io.javalin.Context
 import io.javalin.NotFoundResponse
@@ -45,6 +46,7 @@ constructor(
     private val contactManager: ContactManager,
     private val webSocketController: WebSocketController,
     @DatabaseExecutor private val dbExecutor: Executor,
+    private val objectMapper: ObjectMapper,
     private val clock: Clock
 ) : MessagingController, EventListener {
 
@@ -60,7 +62,7 @@ constructor(
     override fun write(ctx: Context): Context {
         val contact = getContact(ctx)
 
-        val message = ctx.getFromJson("text")
+        val message = ctx.getFromJson(objectMapper, "text")
         if (utf8IsTooLong(message, MAX_PRIVATE_MESSAGE_TEXT_LENGTH))
             throw BadRequestResponse("Message text is too long")
 

briar-headless/src/test/java/org/briarproject/briar/headless/ControllerTest.kt

 package org.briarproject.briar.headless
 
+import com.fasterxml.jackson.databind.ObjectMapper
 import io.javalin.Context
 import io.javalin.core.util.ContextUtil
 import io.mockk.mockk
@@ -30,6 +31,8 @@ abstract class ControllerTest {
     private val response = mockk<HttpServletResponse>(relaxed = true)
     private val outputCtx = ContextUtil.init(request, response)
 
+    protected val objectMapper = ObjectMapper()
+
     protected val group: Group = getGroup(getClientId(), 0)
     protected val author: Author = getAuthor()
     protected val localAuthor: LocalAuthor = getLocalAuthor()

briar-headless/src/test/java/org/briarproject/briar/headless/blogs/BlogControllerTest.kt

@@ -23,7 +23,7 @@ internal class BlogControllerTest : ControllerTest() {
     private val blogPostFactory = mockk<BlogPostFactory>()
 
     private val controller =
-        BlogControllerImpl(blogManager, blogPostFactory, identityManager, clock)
+        BlogControllerImpl(blogManager, blogPostFactory, identityManager, objectMapper, clock)
 
     private val blog = Blog(group, author, false)
     private val parentId: MessageId? = null

briar-headless/src/test/java/org/briarproject/briar/headless/forums/ForumControllerTest.kt

@@ -16,7 +16,7 @@ internal class ForumControllerTest : ControllerTest() {
 
     private val forumManager = mockk<ForumManager>()
 
-    private val controller = ForumControllerImpl(forumManager)
+    private val controller = ForumControllerImpl(forumManager, objectMapper)
 
     private val forum = Forum(group, getRandomString(5), getRandomBytes(5))
 

briar-headless/src/test/java/org/briarproject/briar/headless/messaging/MessagingControllerImplTest.kt

@@ -38,6 +38,7 @@ internal class MessagingControllerImplTest : ControllerTest() {
         contactManager,
         webSocketController,
         dbExecutor,
+        objectMapper,
         clock
     )