From ddca1f5c68e112928d715e1aee2758c40e14fb51 Mon Sep 17 00:00:00 2001
From: Christian Grothoff <christian@grothoff.org>
Date: Sun, 19 Aug 2018 14:19:17 +0200
Subject: [PATCH] add logic to allow fakebank transfers to be retried

---
 src/benchmark/taler-exchange-benchmark.c      |  5 +-
 .../testing_api_cmd_fakebank_transfer.c       | 93 +++++++++++++++++++
 src/include/taler_testing_lib.h               | 14 +++
 3 files changed, 110 insertions(+), 2 deletions(-)

diff --git a/src/benchmark/taler-exchange-benchmark.c b/src/benchmark/taler-exchange-benchmark.c
index c7dbdb4d8..4a664da52 100644
--- a/src/benchmark/taler-exchange-benchmark.c
+++ b/src/benchmark/taler-exchange-benchmark.c
@@ -70,13 +70,14 @@ enum BenchmarkError {
 #define FIRST_INSTRUCTION -1
 
 #define CMD_TRANSFER_TO_EXCHANGE(label, amount) \
-   TALER_TESTING_cmd_fakebank_transfer (label, amount, \
+   TALER_TESTING_cmd_fakebank_transfer_retry \
+    (TALER_TESTING_cmd_fakebank_transfer (label, amount, \
      exchange_bank_account.bank_base_url, \
      USER_ACCOUNT_NUMBER, \
      exchange_bank_account.no, \
      "dummy_user", \
      "dummy_password", \
-     "http://example.com/")
+     "http://example.com/"))
 
 /**
  * Information about an account extracted from a payto://-URL.
diff --git a/src/exchange-lib/testing_api_cmd_fakebank_transfer.c b/src/exchange-lib/testing_api_cmd_fakebank_transfer.c
index 28449d519..4e7812aec 100644
--- a/src/exchange-lib/testing_api_cmd_fakebank_transfer.c
+++ b/src/exchange-lib/testing_api_cmd_fakebank_transfer.c
@@ -120,9 +120,56 @@ struct FakebankTransferState
    * transfer subject).
    */
   const char *config_filename;
+
+  /**
+   * Task scheduled to try later.
+   */
+  struct GNUNET_SCHEDULER_Task *retry_task;
+
+  /**
+   * How long do we wait until we retry?
+   */
+  struct GNUNET_TIME_Relative backoff;
+
+  /**
+   * Was this command modified via
+   * #TALER_TESTING_cmd_fakebank_transfer_with_retry to
+   * enable retries?
+   */
+  int do_retry;
 };
 
 
+/**
+ * Run the "fakebank transfer" CMD.
+ *
+ * @param cls closure.
+ * @param cmd CMD being run.
+ * @param is interpreter state.
+ */
+static void
+fakebank_transfer_run (void *cls,
+                       const struct TALER_TESTING_Command *cmd,
+                       struct TALER_TESTING_Interpreter *is);
+
+
+/**
+ * Task scheduled to re-try #fakebank_transfer_run.
+ *
+ * @param cls a `struct FakebankTransferState`
+ */
+static void
+do_retry (void *cls)
+{
+  struct FakebankTransferState *fts = cls;
+
+  fts->retry_task = NULL;
+  fakebank_transfer_run (fts,
+                         NULL,
+                         fts->is);
+}
+
+
 /**
  * This callback will process the fakebank response to the wire
  * transfer.  It just checks whether the HTTP response code is
@@ -151,6 +198,27 @@ add_incoming_cb (void *cls,
   fts->serial_id = serial_id;
   if (MHD_HTTP_OK != http_status)
   {
+    if (GNUNET_YES == fts->do_retry)
+    {
+      if ( (0 == http_status) ||
+           (TALER_EC_DB_COMMIT_FAILED_ON_RETRY == ec) ||
+	   (MHD_HTTP_INTERNAL_SERVER_ERROR == http_status) )
+      {
+        GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                    "Retrying fakebank transfer failed with %u/%d\n",
+                    http_status,
+                    (int) ec);
+	/* on DB conflicts, do not use backoff */
+	if (TALER_EC_DB_COMMIT_FAILED_ON_RETRY == ec)
+	  fts->backoff = GNUNET_TIME_UNIT_ZERO;
+	else
+	  fts->backoff = GNUNET_TIME_STD_BACKOFF (fts->backoff);
+	fts->retry_task = GNUNET_SCHEDULER_add_delayed (fts->backoff,
+                                                        &do_retry,
+                                                        fts);
+	return;
+      }
+    }
     GNUNET_break (0);
     GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                 "Fakebank returned HTTP status %u/%d\n",
@@ -328,6 +396,11 @@ fakebank_transfer_cleanup (void *cls,
                 cmd->label);
     TALER_BANK_admin_add_incoming_cancel (fts->aih);
   }
+  if (NULL != fts->retry_task)
+  {
+    GNUNET_SCHEDULER_cancel (fts->retry_task);
+    fts->retry_task = NULL;
+  }
   GNUNET_free (fts);
 }
 
@@ -633,4 +706,24 @@ TALER_TESTING_cmd_fakebank_transfer_with_instance
   return cmd;
 }
 
+
+/**
+ * Modify a fakebank transfer command to enable retries when the
+ * reserve is not yet full or we get other transient errors from the
+ * fakebank.
+ *
+ * @param cmd a fakebank transfer command
+ * @return the command with retries enabled
+ */
+struct TALER_TESTING_Command
+TALER_TESTING_cmd_fakebank_transfer_retry (struct TALER_TESTING_Command cmd)
+{
+  struct FakebankTransferState *fts;
+
+  GNUNET_assert (&fakebank_transfer_run == cmd.run);
+  fts = cmd.cls;
+  fts->do_retry = GNUNET_YES;
+  return cmd;
+}
+
 /* end of testing_api_cmd_fakebank_transfer.c */
diff --git a/src/include/taler_testing_lib.h b/src/include/taler_testing_lib.h
index 0db27d0e6..83523dfc4 100644
--- a/src/include/taler_testing_lib.h
+++ b/src/include/taler_testing_lib.h
@@ -620,6 +620,7 @@ TALER_TESTING_cmd_fakebank_transfer_with_ref
    const char *ref,
    const char *exchange_url);
 
+
 /**
  * Create "fakebank transfer" CMD, letting the caller specifying
  * the merchant instance.  This version is useful when a tip
@@ -664,6 +665,19 @@ TALER_TESTING_cmd_fakebank_transfer_with_instance
    const char *exchange_url,
    const char *config_filename);
 
+
+/**
+ * Modify a fakebank transfer command to enable retries when the
+ * reserve is not yet full or we get other transient errors from the
+ * fakebank.
+ *
+ * @param cmd a fakebank transfer command
+ * @return the command with retries enabled
+ */
+struct TALER_TESTING_Command
+TALER_TESTING_cmd_fakebank_transfer_retry (struct TALER_TESTING_Command cmd);
+
+
 /**
  * Make a "wirewatch" CMD.
  *