v0.2.0 Released

[beef9999]

Photon v0.2.0 has released, this release was mainly focused on network socket, security context and multi-vcpu support.

• Socket refactoring. Now the sockets have a much clearer class hierarchy.
• Remove deprecated TLS socket implementation. Use net/security-context instead.
• Add lock-free ring queue. common/lockfree-queue.h now using by photon Executor and WorkPool.
• WorkPool now support photon thread creating and migration.
• TLSContext now using user-defined BIO to adapt libssl, prevent breaking re-negotiation when duplex usage.
• Bugfix: ExpireContainer find protected by photon lock in case of multi-thread accessing.
• Bugfix: HTTP Proxy now replys 502 when failed forwarding requests.

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This discussion was created from the release v0.2.0.