verjus commented on issue #552:
URL: https://github.com/apache/mynewt-nimble/issues/552#issuecomment-703181598
I am posting here so as to not open a duplicate issue.
I am having the exact same issue, which I solved in a similar manner. I
maintain a list of packets representing the entire payload that I need to
transfer. The total payload is greater than the MTU but not each packet in the
list. I send the first packet via:
```
struct os_mbuf *om = ble_hs_mbuf_from_flat(node->packet.data,
node->packet.dataSize);
int rc = ble_gattc_notify_custom(conn_handle, alexa_notify_handle, om);
```
and wait for the BLE_GAP_EVENT_NOTIFY_TX event. When I receive this event,
I check event->notify_tx.status and send the next packet in the packet list.
If there are still packets left in the list, it will trigger again a notify_tx
even until there are no packets left.
This appears to work. However, when I stress test it by sending 338 bytes
with an MTU of 33, it fails after the 12th packet. The return code is
notify_tx.status = 6, which seems to correspond to BLE_HS_ENOMEM. This would
indicate a heap exhaustion situation. I don't understand how this could be
possible. Aren't the buffers returned to the heap after each call to
ble_gattc_notify_custom? So what am I doing wrong?
Here is how it looks like:
This is the list of packets I am trying to send with a series of
notifications (no indicate):
Packet [1/13] contains: 60 00 00 01 52 18 0a cf 02 0a 24 0a 0f 41 6c 65
78 61 2e 44 69 73 63 6f 76 65 72 79 12 11
Packet [2/13] contains: 60 14 1b 44 69 73 63 6f 76 65 72 2e 52 65 73 70
6f 6e 73 65 12 a6 02 0a a3 02 0a 0e 41 31
Packet [3/13] contains: 60 24 1b 4f 52 32 44 55 50 37 4a 30 35 39 5a 12
0a 4e 69 78 69 65 54 69 6d 65 72 1a 0b 4e
Packet [4/13] contains: 60 34 1b 69 78 69 65 20 54 69 6d 65 72 22 0e 41
58 53 20 49 6e 64 75 73 74 72 69 65 73 5a
Packet [5/13] contains: 60 44 1b 1d 0a 0e 41 6c 65 78 61 49 6e 74 65 72
66 61 63 65 12 06 41 6c 65 72 74 73 1a 03
Packet [6/13] contains: 60 54 1b 31 2e 31 5a 55 0a 0e 41 6c 65 78 61 49
6e 74 65 72 66 61 63 65 12 1a 41 6c 65 78
Packet [7/13] contains: 60 64 1b 61 2e 47 61 64 67 65 74 2e 53 74 61 74
65 4c 69 73 74 65 6e 65 72 1a 03 31 2e 30
Packet [8/13] contains: 60 74 1b 22 22 0a 08 0a 06 74 69 6d 65 72 73 0a
0a 0a 08 74 69 6d 65 69 6e 66 6f 0a 0a 0a
Packet [9/13] contains: 60 84 1b 08 77 61 6b 65 69 6e 66 6f 62 72 0a 01
30 12 40 34 32 37 38 44 43 34 35 34 33 31
Packet [10/13] contains: 60 94 1b 41 33 32 38 41 37 46 41 32 30 44 38 35
36 36 31 36 46 34 44 32 42 37 34 41 44 33
Packet [11/13] contains: 60 a4 1b 34 36 46 35 32 37 42 43 33 34 33 35 36
43 33 37 32 31 33 32 31 38 44 37 43 43 1a
Packet [12/13] contains: 60 b4 1b 01 31 22 0e 41 31 4f 52 32 44 55 50 37
4a 30 35 39 5a 2a 0a 4e 69 78 69 65 54 69
Packet [13/13] contains: 60 c8 11 6d 65 72 32 0c 34 34 30 30 34 39 30 46
36 41 31 30
after the 11th packet, I get:
preparing to send chunk of data size= 30
sending packet number 12 <<<<<<<<
60 b4 1b 01 31 22 0e 41 31 4f 52 32 44 55 50 37
4a 30 35 39 5a 2a 0a 4e 69 78 69 65 54 69
Sending notification now
GATT procedure initiated: notify; att_handle=12
event type= 0x000d
notification update; status=0 <<<<<<<<<< SUCCESS
Notify tx connection_handle = 64
Notify tx attr handle = 12
Notify tx indication = 0
PacketList_send called with:
firstPacket = 0
Resp code = 0
But the following packet (which is the last by design) fails:
Preparing to send chunk of data size= 20
sending packet number 13 <<<<<<<<
60 c8 11 6d 65 72 32 0c 34 34 30 30 34 39 30 46
36 41 31 30
Sending notification now
GATT procedure initiated: notify; att_handle=12
event type= 0x000d
notification update; status=6 <<<<<<<<<< FAILURE
Notify tx connection_handle = 64
Notify tx attr handle = 12
Notify tx indication = 0
PacketList_send called with:
firstPacket = 0
Resp code = 6 <<<
Retry
and never succeed after that.
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