Allow curl handle in CurlHttpClient to be kept alive

[ammarfaizi2]

Thank you so much for this amazing library!

Improvement Proposal

The CurlHttpClient currently produces an excessive number of connect() syscalls, as every makeRequest creates a new TCP connection. This inefficiency becomes particularly evident with TgLongPoll, which continuously calls getUpdates in an endless loop, creating a relentless cycle of connect() and close() operations.

A more sensible approach is to reuse HTTP connections by keeping them alive across multiple requests. I suggest modifying the implementation to allow the curl handle to persist until the CurlHttpClient object is destroyed.

For thread safety, we can maintain a std::unordered_map<std::thread::id, CURL*> curlHandles within the CurlHttpClient class, ensuring each thread gets its own handle.

After all, treating connections like disposable napkins doesn't exactly scream efficiency.

Before this change

So many socket connect() and close() calls:

ammarfaizi2@integral2:~/p/ict-bot/build$ strace -e connect ./ict-bot
connect(9, {sa_family=AF_INET, sin_port=htons(443), sin_addr=inet_addr("149.154.167.220")}, 16) = -1 EINPROGRESS (Operation now in progress)
connect(9, {sa_family=AF_INET, sin_port=htons(443), sin_addr=inet_addr("149.154.167.220")}, 16) = -1 EINPROGRESS (Operation now in progress)
connect(9, {sa_family=AF_INET, sin_port=htons(443), sin_addr=inet_addr("149.154.167.220")}, 16) = -1 EINPROGRESS (Operation now in progress)
connect(11, {sa_family=AF_INET6, sin6_port=htons(443), sin6_flowinfo=htonl(0), inet_pton(AF_INET6, "2001:67c:4e8:f004::9", &sin6_addr), sin6_scope_id=0}, 28) = -1 EINPROGRESS (Operation now in progress)
connect(9, {sa_family=AF_INET, sin_port=htons(443), sin_addr=inet_addr("149.154.167.220")}, 16) = -1 EINPROGRESS (Operation now in progress)
connect(9, {sa_family=AF_INET, sin_port=htons(443), sin_addr=inet_addr("149.154.167.220")}, 16) = -1 EINPROGRESS (Operation now in progress)
connect(11, {sa_family=AF_INET6, sin6_port=htons(443), sin6_flowinfo=htonl(0), inet_pton(AF_INET6, "2001:67c:4e8:f004::9", &sin6_addr), sin6_scope_id=0}, 28) = -1 EINPROGRESS (Operation now in progress)
connect(9, {sa_family=AF_INET, sin_port=htons(443), sin_addr=inet_addr("149.154.167.220")}, 16) = -1 EINPROGRESS (Operation now in progress)
connect(11, {sa_family=AF_INET6, sin6_port=htons(443), sin6_flowinfo=htonl(0), inet_pton(AF_INET6, "2001:67c:4e8:f004::9", &sin6_addr), sin6_scope_id=0}, 28) = -1 EINPROGRESS (Operation now in progress)
connect(9, {sa_family=AF_INET, sin_port=htons(443), sin_addr=inet_addr("149.154.167.220")}, 16) = -1 EINPROGRESS (Operation now in progress)
connect(9, {sa_family=AF_INET, sin_port=htons(443), sin_addr=inet_addr("149.154.167.220")}, 16) = -1 EINPROGRESS (Operation now in progress)
connect(9, {sa_family=AF_INET, sin_port=htons(443), sin_addr=inet_addr("149.154.167.220")}, 16) = -1 EINPROGRESS (Operation now in progress)
connect(9, {sa_family=AF_INET, sin_port=htons(443), sin_addr=inet_addr("149.154.167.220")}, 16) = -1 EINPROGRESS (Operation now in progress)
connect(9, {sa_family=AF_INET, sin_port=htons(443), sin_addr=inet_addr("149.154.167.220")}, 16) = -1 EINPROGRESS (Operation now in progress)
connect(11, {sa_family=AF_INET6, sin6_port=htons(443), sin6_flowinfo=htonl(0), inet_pton(AF_INET6, "2001:67c:4e8:f004::9", &sin6_addr), sin6_scope_id=0}, 28) = -1 EINPROGRESS (Operation now in progress)
connect(9, {sa_family=AF_INET, sin_port=htons(443), sin_addr=inet_addr("149.154.167.220")}, 16) = -1 EINPROGRESS (Operation now in progress)
connect(9, {sa_family=AF_INET, sin_port=htons(443), sin_addr=inet_addr("149.154.167.220")}, 16) = -1 EINPROGRESS (Operation now in progress)
connect(9, {sa_family=AF_INET, sin_port=htons(443), sin_addr=inet_addr("149.154.167.220")}, 16) = -1 EINPROGRESS (Operation now in progress)
connect(9, {sa_family=AF_INET, sin_port=htons(443), sin_addr=inet_addr("149.154.167.220")}, 16) = -1 EINPROGRESS (Operation now in progress)
connect(9, {sa_family=AF_INET, sin_port=htons(443), sin_addr=inet_addr("149.154.167.220")}, 16) = -1 EINPROGRESS (Operation now in progress)

After this change

Connect once, use it as long as possible:

ammarfaizi2@integral2:~/p/ict-bot/build$ strace -e connect ./ict-bot
connect(7, {sa_family=AF_INET, sin_port=htons(443), sin_addr=inet_addr("149.154.167.220")}, 16) = -1 EINPROGRESS (Operation now in progress)

[reo7sp]

Thank you very much! Good job