PortAllocator的作用就是分配端口号。

PortAllocator类关系图

H:\webrtc-20210315\webrtc-20210315\webrtc\webrtc-checkout\src\p2p\base\portallocator.h
PortAllocator:
int candidate_pool_size = 0; 人工设置candidate池大小，默认自动，不设置
std::vector> pooledsessions; 上下文处理集合，分配端口的实际工作就在里面的每个PortAllocatorSession
PortAllocator::CreateSession
-》BasicPortAllocator::CreateSessionInternal
-》PortAllocatorSession* session = new BasicPortAllocatorSession， return session;

创建BasicPortAllocator对象

每个PeerConnection对应一个PortAllocator对象。

构造BasicPortAllocator的参数

BasicPortAllocator的构造函数

PortAllocator的构造函数

const uint32_t kDefaultStepDelay = 1000; // 1 sec step delay.

// CF = CANDIDATE FILTER
enum : uint32_t {
CF_NONE = 0x0,
CF_HOST = 0x1,
CF_REFLEXIVE = 0x2,
CF_RELAY = 0x4,
CF_ALL = 0x7,
};

InitRelayPortFactory

SetConfiguration

初始化PortAllocator

PeerConnection::Initialize

PeerConnection::InitializePortAllocator_n

PortAllocator中的flag

小结